LOS ANGELES (AP) _ One year ago, Hands Across America was billed as the unassailable charity event of the 1980s, a proposed human chain across the United States to raise at least $50 million for the hungry and homeless.

The plan called for scores of celebrities to join 6 million people in a 4,125-mile line on Sunday, May 25, 1986.

Mickey Mouse and Donald Duck joined hands with participants in Disneyland. Kenny Rogers stood in the blistering heat of the Southwest desert, and President Reagan gingerly participated in front of the White House. It was party time at the Queen Mary in Long Beach and Battery Park in Manhattan.

But there were lots of gaps between those end points, and a lot of people simply didn't send in their pledges, resulting in a net of only $15 million for the hungry and homeless after all costs were paid.

Organizers have found themselves on the defensive because the cost of mounting the event was around $14 million to $16 million. Even though the cost was known in advance, its size in relation to lower-than-anticipated donations hurt credibility.

''It was a net good,'' said Robert Hayes of the National Coalition for the Homeless in New York. ''But they spent too much to raise too little and promoted a national extravaganza empty of content.''

Organizers said there were benefits beyond the balance sheet, though: spotlighting the problem of hunger and homelessness in the United States, and raising the spirit of voluntarism throughout the nation.

''It was a magnificent effort,'' said the Rev. Colin Henderson of St. Mary's Episcopal Church in Laguna Beach. ''It raised a lot of money, but the problem is so much bigger than that.'' Henderson's bid for funds for a homeless shelter run by his church was turned down.

The disbursement of funds is still not complete - $3 million for long-range projects is to be doled out in September.

Critics said that because of the relatively small amounts granted to shelters and other organizations, the process should have been speeded up.

But Hands officials, including USA for Africa President Ken Kragen, said the careful reviews that determined how money was spent were a good thing.

''We're extremely proud of the coalition (review) process and how that worked,'' Kragen said in an interview. ''I give an awful lot of credit to our board of directors, who were under tremendous pressure to spend the money fast.''

Officials are still considering the future of the organization after the final $3 million is given out, and it's possible it will simply close its doors.

Hands Across America was the second charity event by USA for Africa, the celebrity-guided organization that earned admiration for raising $53 million in African relief through the song ''We Are The World.''

It was the efficiency of USA for Africa, which gave out some of the ''We Are The World'' funds within the United States, that led people like Hayes to expect faster action after Hands.

''We had a couple of million from USA for Africa, and within two weeks we gave them proposals for 78 cities,'' he recalled. ''That went off without a hitch, and in many places within weeks the money went out and made a concrete difference.''

But Marty Rogol, USA for Africa executive director, said the careful distribution of the Hands money will also make a difference.

''If we had just bought shelter for the nation's 3 million homeless, it (the $15 million) would have lasted one night,'' Rogol said in a statement. ''If we had just bought food stamp meals for the nation's 20 million hungry, it would have provided less than two meals.''

Even a critic like Hayes admits he cannot feel antagonistic to Hands Across America.

''My criticism is warm and affectionate,'' he said. ''Even one sandwich makes a difference, if you're hungry.''