The ad read: "Cornea for sale . . . Please call working days." The price was the equivalent of $40,000.

In this city where the wealthy lavish millions on plastic surgery, the poor are trying to make ends meet by selling their kidneys and corneas.

"It's very simple -- on one side you have the man who has money but no vision, and on the other side is me: vision, but no money," said the man who placed the advertisement and identified himself only as Rubens. "The more people think about it, the more normal it will become," said Rubens, a heavyset man with chestnut eyes.

Since extraction of a living person's cornea will cause blindness in that eye, people donating corneas usually do so by signing permission for the extraction to take place immediately after death. Two months ago, the Brazilian Red Cross sponsored a nationally televised campaign to solicit such cornea donations.

But squeezed by 100 percent inflation and spreading unemployment, Rubens and dozens of Brazilians began recently to place their kidneys and corneas on sale for immediate delivery through newspaper classifieds.

"The economic situation is critical -- three years ago I lived better than now on half my salary today," said Rubens, who supports his wife and child on $300 a month earned working at Rio's international airport.

Rubens calculates that if he gets his asking price he will have enough to pay for his son's education and secure his future as partially handicapped.

Listed under "medicine and health" in classified columns, the kidney and cornea notices often contain such phrases as: "financial problems," "best offer," "urgent," "good health," "perfect vision" and "young."

The spate of offers to sell organs is a new wrinkle in a longstanding controversy here over the still generally legal practice of the poor supplementing meager incomes by selling their blood to slum-based commercial blood banks.

Sirlei Olga dos Santos advertised one of his kidneys for $30,000, and he hopes the sale will be his ticket out of a $180-a-month job as a night watchman on a construction site for a luxury high-rise.

For the last 10 years Santos has worked a series of jobs. His dream job, playing semiprofessional soccer, ended last year when he was kicked in the knee. "When I was young," said Santos, 23, "I thought I had great opportunities, but now my time has passed. This may be a bit disagreeable, but it's the only thing left."

Several potential buyers have called about his kidney, but no one offered enough money. Confirmed sales are hard to come by. Santos said a friend of his in Sao Paulo sold a kidney in 1973 for $40,000.

Health officials have condemned the black market in vital organs, but there appears to be little they can do about it, since under Brazilian law the sellers cannot be punished.

Edelberto Luiz da Silva, legal adviser to the minister of health, warned that a doctor who takes an organ from a living person for later resale faces up to 10 years in jail and can be barred from practising medicine for 10 years.

Local urologists said they would refuse to perform an organ transplant with a donor if they knew that the organ had been bought. The problem is that once buyer and seller reach an agreement on a deal, neither is likely to tell a doctor that a sale is involved.

Another problem, specialists say, is the high chance of rejection. To determine compatibility, an expensive series of immunological tests is required.

Silva predicted recently that newspapers would stop running the ads, but the following Sunday, dailies in Brazil's three largest cities carried ads for corneas and kidneys. The Belo Horizonte newspaper, O Estado de Minas, contained offerings of 10 kidneys and one cornea.

About 75 percent of blood used in Brazilian hospitals is supplied through commercial blood banks, which are usually located in the impoverished outskirts of major cities.

Regular donors are often unemployed and undernourished, and receive $3 and a bowl of soup in payment for about one pint of their blood. Patients in hospitals pay about $60 for the same amount of blood.

Government health studies show that about 30 percent of the blood obtained commercially is contaminated with hepatitis virus and 10 percent with an agent that causes chagas disease, an incurable illness that slowly attacks the heart. Blood transfusions are the largest cause of hepatitis in Brazil. Former president Ernesto Geisel recently contracted the disease from tainted blood.

Brazilian law prohibits the export of blood, but critics have made unconfirmed allegations that up to 75 percent of blood collected commercially here is reprocessed and marketed overseas, primarily in West Germany and the United States.

"Brazil is today the largest exporter of blood in the world," said Nelson Senise, a Rio doctor who has written extensively on blood banks here. "We are selling our blood at banana prices to the industrialized countries."

Last year a documentary film on the blood business drew large audiences and provoked a national debate.

Entitled "Down to the Last Drop," the movie recreates a factual incident involving Jucenil Navarro de Souza, 33, an unemployed Rio resident who regularly earned money to feed his family by selling his blood. One day after selling blood, Souza dropped dead of anemia at the door of a supermarket.

Following the publicity surrounding the movie, the municipality of Sao Paulo banned commercial blood banks, and the federal government joined the Brazilian Red Cross in a campaign to spur voluntary donations at state health centers.

"If 4 percent of the Brazilian population donated blood, the commercial banks would disappear." Red Cross President Mavy Harmon said in an interview. In Rio, the blood banks are still doing a booming business, with some estimates of traffic running as high as 10,000 liters a day.

In the suburban slum of Madureira, the Natal blood bank faces the local railroad station, which is used daily by thousands of lower-class commuters. At the end of the line, facing the downtown rail terminal, stands another blood bank. Some people have admitted selling blood to pay the 10-cent train fare.

As a reform measure last year, the government created city inspection teams, but a recent visit to the Natal bank found little evidence of the cleanup. In the third-floor walkup, 12 men sat in a waiting room, bare except for a large crayoned price list: $3 for Rh positive, $4 for Rh negative. In the registration room, the floors were dirty, the walls were greasy to the touch, and a box of garbage sat in an open window.

Critics charge that the employes who handle the money also handle the needles. In this bank an open box of medical tubes sat next to the cash box. The director refused to answer questions and asked two reporters to leave.

The director wore a T-shirt inscribed "Portela," and the bank owner, Osmar Jose do Nascimento, is the son of the former president of the Portela samba association. Last year, health officials charged that Nascimento coerced samba dancers into giving blood to finance their costumes for Rio's carnival.

Nascimento brushed off the charges, saying: "A donation of blood wouldn't even cover the cost of a pair of shoes."