The aqueous alcoholic extract of the bulbus of Merendera caucasica showed a high antitumor activity against in vivo 3PS test system. Although, the highest activity was later found in the alkaloidal part, the aqueous fraction which contains proteinaceous compounds, amino acids and some sugars, also showed a moderate activity. This aqueous part was studied in order to evaluate the activity. 'As a result of the routine screening of the Turkish plants, the aqueous extract of the bulbus of Merendera caucasica (Liliaceae) showed a high antitumor activity' (150 mg/kg doses 240%).The aqueous extract of the bulbus of this plant have been used in the treatment of the malignant disease in the eastern part of Turkey for centuries. The fractionation of the crude extract revealed that the activity is in the crude alkaloidal mixture2 (22 mg/kg doses 222 and 14 mg/kg doses 190%). Some activity was also found in the remaining aqueous part (400mg/kg doses 169%). Preliminary studies showed that this part contains amino acids, sugars and proteinaceous compounds. Since, in some early studies, ULUBELEN et al. (1965, 1966, 1967), antitumor active proteinaceous substances were isolated from the plants, it was decided to examine and evaluate the aqueous fraction of the extract.After the separation of alkaloids, the aqueous part of the plant extract was precipitated by the addition of alcohol. The precipitate was fractioned in a sephadex column, two main and four small proteinaceous compounds were obtained (Fig. 1). The main compounds were studied, the first of these ~ielded seven, the second thirteen amino acids. Glutamic, aspartic acids and threonine were highest in amount in compound I1 (Table I). The solution contains glucose, fructose, mannose and saccharose as sugars and thirteen amino acids, proline being the highest in amount.Animal tests in each fraction showed that the proteinaceous mixture had no activity, on the other hand aqueous alcoholic fraction which has amino acids and sugars still showed a moderate activity (400 mg/kg doses 169%).1 The tests have been performed by NIH, Washington DC, USA. The fractionation of the crude alkaloidal mixture and the animal tests are still going on.