In the period 1975-1977 forms of the fungus <i>Botrytis cinerea</i> were found in Poland resistant to benzimidazole fungicides. The incidence of the resistant forms increases with the more intensive use of these fungicides. The resistance of <i>Botrytis cinerea</i> to benzimidazole compounds is a cross-resistance involving the whole group of these agents, nowithstanding wihich of them was applied. The resistance acquired by the fungus does not change its reaction to other prophylactic fungicides.