The objective of this work was to study the effects of calcium salts on growth, sclerotia production, carpogenic germination and infectivity of  Sclerotinia sclerotiorum (Lib.) de Bary ascospores. Morphological and pathological variability was induced to the fungus by calcium salts. Effects of calcium were varied with various calcium forms and their concentrations tested. Calcium acetate was the most effective to inhibit growth of the fungus, which expressed as linear growth on agar medium or mycelial dry weight onto liquid medium. On the other hand, calcium phosphate showed the highest inhibitory effect toward sclerotia production by the tested fungus grown onto either solid or liquid media. Since it caused 75% inhibition for sclerotia production at 4000 ppm and completely prevented sclerotia production at 8000 ppm. Otherwise, calcium chloride provided the highest inhibitory effect to carpogenic germination. Also, number of apothecia was greatly affected by calcium acetate, calcium oxide and calcium carbonate. Moreover, infectivity of S. sclerotiorum  ascospores was varied with calcium salts tested. Calcium phosphate and calcium oxide were the most suppressive to ascospores infectivity.