D.C. Mayor-elect Marion Barry, who relied heavily on affluent white voters to defeat his opponents in last September's Democratic primary, drew his strongest support from poor, black precincts of the city to win Tuesday's general election, an analysis of election results shows.

Breaking from their voting pattern in the primary, blacks in some of the poorest areas of the city voted almost unanimously for Barry over Republican challenger Arthur Fletcher, while Barry lost almost half the precincts in affluent, predominantly white and heavily GOP Ward 3 west of Rock Creek Park to Fletcher.

"So much for Barry being the 'white man's candidate,'" said one Barry campaign organizer yesterday, a reference to some critics' descriptions of Barry as seeking white liberal and business support by toning down his image as a one-time militant firebrand.

In the Democratic primary, white voters both in and out of Ward 3 surprised election observers by opting for Barry over incumbent Mayor Walter E. Washington and City Council Chairman Sterling Tucger. The closed primary, however, masked the large white vote potential for Republican candidates in the city. That vote, in the direct contest with Democrats in Tuesday's general election, demonstrated its considerable conservative strength here.

Barry took the city by a landslide, winning 130 pf 137 precincts. But the seven precincts that Fletcher did win were all in Ward 3 and in the most affluent parts of Ward 3 - Wesley Heights, American University Park and lower Cleveland Park. Barry barely took the ward as a whole, getting 51 per cent of the vote, while he averaged more than 70 percent of the vote in the rest of the city.

At the other end of the city, both geographically and socially, poor and heavily black precincts in far Southeast voted overwhelmingly for Barry in Tuesday's general election. But those same precincts rejected him in the September primary, preferring Mayor Walter Washington instead.

Voters in Precincts 119, 120, 121 and 122, embracing the Wheeler Road-Congress Heights-St. Elizabeths Hospital area, for example, cast 85 percent of their ballots for Barry.

Ward 2, which straddles the center of the city from Dupont Circle to Capitol Hill, exemplifies the contrasting range of socioeconomic conditions affecting the vote for Barry and Fletcher.

In Precinct 131, for example, a sprawling industrial area scattered with dilapidated public housing projects just south of the Capitol along the Anacostia River, 92 percent of the voters went for Barry.

In Precinct 130, just north of 131 but embracing the expensively refurbished 19th century homes clustered around the Capitol building, only 65 percent of the vote went for Barry while 31 percent went to Fletcher.

Precinct 129, Fletcher's home precinct in new Southwest, contains a hodge podge of relatively new affluent apartment buildings and aging public housing. Barry won 60 percent of the vote there and Fletcher 38 percent.

Barry's showing was even weaker in Precincts 2 and 3, the Foggy Bottom area with its sprawl of apartment buildings inhabited largely by students, young singles and senior citizens. Barry received about 53 percent of the vote compared to Fletcher's 43 percent.

The precincts to the east and north from Dupont Circle to lower Shaw showed greater support for Barry. In predominantly white more affluent Precinct 14 west of Dupont Circle, Barry received 66 percent of the vote and 84 per cent in Precinct 21 in lower Shaw between 13th Street and Florida Avenue NW, a large black area.

Fletcher's best showing among the seven precincts he won occurred in Precinct 9, American University Park, where he won 68 per cent of the votes.