Abstract: The paper deals with the effect of different concentration of calcium on the growth, nitrate absorption, NR activity and the contents of calcium and magnesium of the Cucumis sativus cotyledon callus. The results showed that the growth, nitrate absorption and NR activity are much lower in the deficiency caleium calf, s than the normal callus, These results were similar to that obtained with whole plants. The results obtained was discussed.