This country's leftist revolutionaries are still fighting after nearly six years of warfare because of memories of vicious repression, the conviction that the rich still run the country and a vague vision that life would be better under a "people's government."

Most veteran guerrillas and their peasant supporters seem ready to fight indefinitely, but they do not appear to be attracting many new recruits. A large majority of militants interviewed during a nine-day trip behind guerrilla lines had joined the left during its upsurge in the 1970s and early 1980s.

These long-time radicals, who describe themselves as a revolutionary vanguard, dismiss recent reforms in El Salvador as inadequate, halfway measures. Having broken ties long ago with their families and the mainstream of Salvadoran society, they have committed all of their personal energies to seeking victory.

When pressed, some rebels admitted that the three elections held in El Salvador since 1982 were not openly rigged by the armed forces as in the past. But they argued that the Christian Democratic government of President Jose Napoleon Duarte is a smokescreen for continued control by the military and the oligarchy, the term used here to describe the powerful class of wealthy landowners and businessmen.

"Duarte says there's democracy now, but it's a lie. We're still the poor. Nothing has changed," said poor farmer Oscar Martinez. One day a week, usually "Red Saturday," as it is called, he and other men till patches of corn, beans and rice set aside for the guerrillas.

The guerrillas do not talk in specific terms about how they would reorganize society if they won, partly because they know that they are nowhere close to victory. Their proposals for a negotiated peace settlement, like Duarte's offers, seem to be designed mainly for public relations and not as a realistic starting point for serious talks.

"The reasons for our conflict are rooted in a deep social inequality," rebel commander Leonel Gonzalez said. "If the roots of the conflict do not disappear . . . then a solution would not be just, and would not end the conflict."

It is clear that the Salvadoran guerrillas' leadership is Marxist-Leninist in its political orientation. The Salvadoran left is more openly radical than Nicaragua's Sandinistas were when they came to power in 1979.

The reason is that the Sandinistas made an alliance with Nicaraguan business and professional groups to oust the widely despised Somoza family dictatorship.

El Salvador's Farabundo Marti National Liberation Front has little support among this country's wealthy and professional classes.

For many of El Salvador's rebels, the most compelling reason for their struggle is to avenge the deaths of loved ones. Since 1979, the Army, military security forces, civil defense personnel and right-wing vigilante groups called death squads are estimated to have killed more than 30,000 people who were fingered as guerrillas or leftist sympathizers.

"My younger brother joined the guerrillas, so they the military persecuted me. It was dangerous, so I joined as well in 1977. My father was killed in 1982 because all four of his sons were guerrillas," a rebel militiaman using the name Reyes said.

The rebels' determination to fight on can be chilling.

For example, one revolutionary song with a catchy tune praises the Belgian-made FAL automatic rifle: "Yes, comrade, the FAL is good; to eliminate the criminal." In another, a guerrilla sings that he has come from afar "to do away with the bourgeoisie."

Following are thumbnail sketches of four longtime radicals in the movement, their reasons for joining and for staying now. The Commander

Like many guerrilla commanders, Ricardo, 36, was a middle-class youth who became radicalized while attending university in San Salvador in the early 1970s.

Tall and thin, with a bushy black beard and thick eyeglasses, he now is the guerrillas' political-military director for the northern province of Chalatenango.

"My parents had to work very hard to stay afloat," he said. They were both teachers, a profession that has yielded many Salvadoran revolutionaries including Ricardo's boss Gonzalez.

"I arrived at the conclusion that, with the great majority of the people suffering hunger, it was necessary for all the people to radically change the structure of the society," Ricardo said.

After the military detained him briefly for working as a peasant organizer, he entered clandestine life in 1974.

"My [real] name is already forgotten," he said. "I haven't seen my family since 1977."

Ricardo acknowledged that many peasant families, tired of suffering air and infantry attacks, were leaving the province for which he is responsible.

But he argued that they still support the revolution, and that they will continue to work with the guerrillas from their new homes in refugee camps or in government-dominated territory. The Peasant

Oscar Martinez, 30, an "organized" peasant, delivered his third daughter under a tree in the forest in May while hiding from Army troops that were making a sweep through the area. He used a razor blade to cut the umbilical cord after his wife spent nearly 24 hours in labor in the open.

"I told her that I hoped that the enemy was a long way away so that they wouldn't hear her groans," Martinez said. "I know if the enemy captures me, they'll kill me, because I collaborate with the boys," using a common slang term for the guerrillas.

Asked why he puts up with such hardship to grow food for the rebels, Martinez said simply, "They need support from us." He said he joined the left in 1975 after quitting a job as a coffee picker because the landowner cheated him at the scales when his daily total was weighed, and because the pickers once were fed mice at their noonday meal.

"My work is the hoe. I am a campesino for the people," he said. The Organizer

Maria Serrano, 35, was an ardent Duarte supporter in the 1972 presidential elections. Duarte won at the ballot box, but, it is now generally accepted, the armed forces stole his victory from him.

Serrano and many other current revolutionaries left mainstream politics then because of disgust over the fraud.

"At that time, the people loved Duarte. They saw him as an alternative," Serrano said. "I was a militant for the Christian Democrats with all my heart and soul. Now I'm the same way for the local popular government."

Serrano, stocky and with a quick smile, is one of the most important organizers in this rebel stronghold. In September 1983, after two years as head of the local women's organization, she was elected the first president of the "popular" government.

Today she is an adviser to that government, and lives a nomadic life walking continually from village to village. She recruits people for new tasks, hears their complaints, and spreads news and gossip throughout the guerrillas' "zone of control."

Serrano, who was born in the nearby town of Arcatao, had to go to work as a servant at the age of 9 to earn money for her family.

"Those U.S. congressmen who approved aid for Duarte deserve to be in a good bombardment so they'll know what it's like," she said. The Guerrilla

Teodoro Hernandez was 13 years old in 1975 when he joined a radical peasant union in his native province of San Vicente in central El Salvador.

Five years later he became a guerrilla, and now, at the age of 23, he commands a unit of 100 men in one of the guerrillas' two elite brigades.

"I'd say I've been in about 20 battles," he said. He received a slight shrapnel wound in the rebels' successful attack on the Cerron Grande dam in June 1984.

Hernandez said that all four of his brothers also were guerrillas on various fronts.

A sister and another brother died at the ages of 5 and 2 respectively in 1974 because of malnutrition, he said.

"My parents, from the beginning, were poor," he said. "I saw in our country that there wasn't a government capable of resolving the problems of poverty and health."

In camp, Hernandez said, the guerrillas clean their rifles, play dice games and chess, listen to the radio, and wonder when they'll get leave to visit their girlfriends.

He hasn't seen his in two months, but said: "One suffers many sacrifices, but in the end we will achieve the liberation of our people."