Things have changed markedly in many communist nations in recent years - changes that would have been hard to imagine a decade or two ago. The wholesale resignation of the leaders of Yugoslavia this week in the midst of an economic crisis is just the latest example.

Premier Branko Mikulic and his entire 31-member Cabinet quit in protest after the Yugoslavian Parliament refused to pass an economic reform law needed to ensure continued help from the International Monetary Fund.This is the sort of thing that happens with regularity in certain democracies, but it is a historic first in Yugoslavia since the Communist Party took power after World War II.

The resignations are seen as leading to a possible further liberalization of Yugoslavia's one-party system. Mikulic had taken over as premier in 1986 for a four-year term. Parliament and the nine-member presidency must now decide on whom to choose as his replacement.

Yugoslavia is badly in debt, has 250 percent annual inflation, and suffers from 15 percent unemployment. It has endured more than 1,000 strikes in 1988, and has seen ethnic uprisings in the diverse provinces and "republics" that make up the country. Mikulic had wanted an austerity program and cuts in public spending in order order to qualify for further IMF loans. Parliament's refusal left his program in shambles.

Despite the political changes, Yugoslavia's economic problems - like those of other communist-run countries - stem from the heavy hand of a central bureaucracy. The Parliament apparently has recognized this. Along with accepting Mikulic's resignation, it adopted a new law stimulating private enterprise - "the first step toward a market economy," according to the state-run news agency.

A possible multi-party system and free enterprise? The late Marshal Tito would never recognize the communist state he fashioned after World War II.