Glycoalkaloids are naturally occurring toxicants in plants that are members of the Solanaceae family. In this paper occurrence of glycoalkaloids, especially solanine and chaconine in potatoes and tomatoes, were reviewed. Basing on literature, toxicological properties and methods of determination were reported. Attention was paid to common content of glycoalkaloids in potatoes and tomatoes and their commercial products. Solanine and chaconine are usually present at low levels in large majority of current commercial varieties but they can accumulate to high levels in greened, stored, damaged potatoes. High concentration may cause acute poisoning, including gastro-intestinal and neurological disturbances, in man. The upper limit, recognized as a safe (non-toxic), was presented. According to WHO normal levels in potatoes 20-100 mg per kg of potatoes is not of toxicological concern.