Voter registration in Virginia is up slightly this year from 1981, when the state last elected a governor, according to figures released yesterday. But some analysts, citing a drop in absentee ballots cast so far in this race, are predicting a low turnout when voters choose a governor Nov. 5.

According to the State Board of Elections, there were 99,070 new registrants in the state this year. That figure represents an increase from 1981, when 93,676 signed up to vote. This year's cut-off date for registration was Oct. 5.

Despite the slight increase, registrars across the state have expressed disappointment with the results. They say that changes in state law three years ago have made registering to vote in Virginia much easier, and should have led to higher levels of registration this year.

"The bottom line is that the numbers are nothing to cheer about," said Richard D. Taylor, director of the voting rights project of the Virginia Chapter of the American Civil Liberties Union.

"Registrars all over the state feel it's slow right now," said a State Board of Elections official who asked not to be named.

The official said that the number of absentee votes cast is generally thought to be a reliable portent of voter turnout.

The sharpest jump in registrations occurred in Fairfax County, by far the state's largest locality. The county signed up 18,806 new voters this year, compared to 12,371 in 1981 -- an increase of about 50 percent.

Nonetheless, said Fairfax Registrar Lilyan Y. Spero, "It was slower than I had hoped." She added, "I think excitement is starting to build now, but it's too late."

A recent poll by The Washington Post showed that Virginia voters have shown little enthusiasm for the current campaigns, in which neither candidate for governor, Democrat Gerald L. Baliles and Republican Wyatt B. Durrette, has emerged as a figure as popular as Gov. Charles S. Robb. Robb cannot serve consecutive terms under state law.

In the current issue of The Economist, the respected British weekly news magazine, an article on the Virginia gubernatorial race carries the headline: "Tweedledum and (Yawn) Tweedledee."

Del. Vincent F. Callahan Jr. (R-Fairfax) said, "There is a lack of enthusiasm for the gubernatorial candidates. There aren't any burning issues; the economy is good and unemployment is low."

Callahan called Baliles and Durrette "two solid candidates who don't have the charisma of Ronald Reagan . . . . "

Jerry Shaw, director of the Republican Joint Campaign Committee, said the GOP plans a major drive to get voters to the polls on election day.

Some observers have said that party leaders, who orchestrated major registration drives during last year's presidential election campaign, have chosen to concentrate instead this year on getting out the vote.

Shaw denied that registration had been given second priority.