American women still do most of the cooking, laundering and housecleaning, but men have accepted an increased share of other household chores such as pet care, gardening and dealing with bills, a university study shows.

Overall, American women do two hours of housework for every one hour put in by a man, according to the report by sociologist John P. Robinson of the University of Maryland.Robinson's findings, based on his 1985 survey of 5,000 men and women, compare to earlier, similar studies at the University of Michigan which said that women performed a 3-to-1 share of housework in 1975 and nearly 6 to 1 in 1965.

All three analyses found four primarily female tasks - cooking meals, cleaning up after meals, housecleaning and laundry.

Men dominated two areas: yard work and home repairs, Robinson found.

And two areas where women previously did the majority of the work - physically dealing with bills and the combined category of gardening and pet care - were about evenly divided in the most recent report.

"Several important trends account for shifts in who does how much housework," Robinson said. These include declines in the share of households with children, a smaller share of married-couple households and the increasing number of women in the paid workforce.

Robinson's study is reported in the December edition of American Demographics magazine, which concentrates on population and statistics issues.

In 1985, Robinson found, men averaged 9.8 hours of housework weekly, while women put in 19.5 hours.

The 1975 study found men working 7.0 hours a week on home tasks compared to 21.7 hours for women.

And a decade earlier, men spent 4.6 hours a week on housework, compared to 27.0 hours for women.

But despite the increasing male share of the load, men and women still tended to observe traditional separations of tasks. For example, in 1965 some 98 percent of washing and ironing was done by women, while by 1985 that was only down to 88 percent. Women did 87 percent of cooking in 1965, and 77 percent in 1985.

On the other hand, men did only 32 percent of the bill-paying chores in 1965 but increased their share to 53 percent by 1985.

And men did 53 percent of the gardening and pet care in 1985, up from 33 percent two decades earlier.

Women with children under age 5 averaged 22.5 hours of gousework weekly in 1985, compared to 19.9 hours for women with children over age 5 and 17.9 hours for childless women. All three figures are down from prior years.

The studies show that getting married in 1965 increased a woman's housework time from 15.5 hours weekly to 31.6 hours. Men on the other hand, eased their burden a bit, average 4.7 hours when single and only 4.5 hours after getting married.

By 1985, marriage increased the housework for women from 14.9 hours to 22.4 hours, while men worked 7.9 hours on housework when single and 11.1 hours after getting married.

In 1965 a housewife averaged 34 hours of housework a week, compared to 17.8 hours for women with paid jobs. By 1985 that had declined to 23.6 hours for the women at home and 14.7 hours for those with jobs.