About the same percentage of registered voters cast ballots Tuesday in Montgomery and Prince George's counties as in the 1974 Maryland primaries, but election officials and party workers said they were disappointed with the turnout, which was well below statewide voting percentages.

In the District of Columbia, more than 46 percent of the city's 195,000 registered Democrats voted in the close mayoral primary among Marion Barry, Walter Washington, and Sterling Tucker, according to unofficial results.

In Maryland, however, unofficial figures showed that about 37 percent of Democrats and 26 percent of Republicans voted in Montgomery County, while 38 percent of Democrats and 28 percent of Republicans voted in Prince George's, election officials said. Statewide, the voting percentages were 43 for the Democrats and 30 for the Republicans.

The highest voter turnout in the District's mayoral primary was in Ward 4, where 16,956 Democrats, or 53 percent of the total registered, voted for mayor. Ward 5 recorded a Democratic turnout of 49.5 percent, while Ward 8 had the lowest turnout figure, 33.5 percent. All three percentages will increase when absentee votes are included.

One of the highest - and perhaps most crucial - voting percentages in Maryland was recorded in Baltimore County, where about 51 percent of Democrats voted, according to unofficial figures. Harry Hughes, who won the gubernatorial nomination, collected almost 70,000 votes in the county, 38,000 more than Acting Gov. Blair Lee III, who finished second.