This study analyzes the determinants of changes in Finnish agricultural protection and investigates a series of theoretical hypotheses concerning the determinants of agricultural protection. Our empirical econometric analysis uses annual data from 1931 to 1990 for 9 agricultural commodities. The results support the hypotheses that changes in agricultural protection are induced by changes in the structure of the economy which affect the distribution and the size of costs and benefits of protection. Variables that measure the impact of those changes, such as relative income in agriculture, the share of farmers in the employment, the share of food in total consumers expenditure, and the self sufficiency rate, are found to be empirically important.