Studied potatoes of seven coloured fleshed varieties contained less than 300 mg kg鈭? d.w. glycoalkaloids. TGA levels in red-fleshed potato varieties were statistically higher by about 8%compared with the blue-fleshed varieties. The proportion between 伪-solanine and 伪-chaconine in potato tubers and in processed potato was found to stabilize in the ranges from 1.0:1.8 (Blue Congo variety) up to 1.0:2.2 (Rosalinde variety), and the highest changes of proportion between 伪-solanine and 伪-chaconine in crisps were stated. The peeling process decreased the TGA content in tubers independently on studied potato variety, in average about 20%, cooking of un-peeled potato about 8%and cooking peeled potato about 39%, comparing with a raw material. Higher decreases of TGA were found in fried products (mean about 83%in crisps, about 92%in French fries after I stage of frying and about 94%in ready French fries).