A market share model for the Japanese imported beef was constructed to estimate the effects of political manipulation of import quotas and price competition on market shares of Australia, the United States and New Zealand .. The Japanese demand for imported beef was ~lso estimated, using quarterly data from 1978 through 1987, and reductions of the wholesale price of imported beef were calculated to estimate the extent of market expansion for imported beef in Japan, had the market been liberalized in 1979. The demand function for imported beef and the market share model were then utilized to estimate Japanese imports of beef from Australia, the United States and New Zealand under partial and complete trade liberalization, had them been implemented in 1979. Empirical results suggest that Australia and New Zealand could have captured bigger shares, at the expense of the United States, of an expanded market in Japan. It was found to be possible that the Japanese imports of beef from the United States could have actually declined under partial trade liberalization.