The D.C. public schools ranked last in a comparison of graduation rates for states across the nation, according to a report released yesterday by the National Center for Education Statistics, but Washington may fare well when compared with other large cities.

The study compared the number of high school graduates in the 1980-81 school year with the ninth grade enrollment in 50 states and the District in the fall of 1977. Spokesmen at the center said most of the students who were not listed as graduating in 1981 were dropouts, but added that some may simply have been held back a year or perhaps graduated early.

The District ranked last with a 54.6 percent graduation rate that compared with the national average for states of 72 percent. The center's report said that Minnesota ranked highest with 86 percent and that Maryland and Virginia schools ranked 24th and 28th respectively with rates of 75 percent and 73.3 percent.

Vance Grant, head of the statistical information office of the National Center for Education Statistics, the statistical arm of the U.S. Department of Education, said the District's graduation rates can be misleading in relation to the national average for states and the individual state's figures since large cities traditionallly have lower graduation rates than states.

Grant added that students who leave the District for other school systems are automatically dropped from the city's graduation numbers, while a student who moves from jurisdiction to jurisdiction in a state would still be counted in that state's totals.

"If you were comparing D.C. to other cities they would be more in the ball park," Grant said.

The center has not done a similar comparison of graduation rates for large cities since 1977, Grant said. In that report, the District fared well with a percentage of 59.9 as compared with Baltimore, 55.3 percent; Philadelphia, 60; and New York City, 51.3.

Janis Cromer, spokesman for the D.C. school system, said the period of the center's report on states was also a time "when D.C. lost a number of families who simply left the area." She also said that it was unfair to compare the District's figures with those of states.

Mississippi ranked worst of the states in the report, according to Grant, with a graduation percentage of only 61.8 percent.

"This is not exactly precise," Grant said of the report, "but it gives us some indication of where school completion rates are highest and lowest." He said the socio-economic status of youths in some poorer states was a contributing factor to their lower graduation rates.