In a group of patients after transplantation of the kidney with stabilized graft function treated by Consupren sol. combined with prednisone and azathioprin in 20 patients (group A) Consupren sol. was replaced by Consupren S capsules, in 17 patients (group B) Consupren sol. therapy proceeded without any change. To maintain the cyclosporin blood concentration within the therapeutic range it was necessary after the change of drug form in group A to adjust the dosage of the drug in 12 patients of group A while in group B only in one patient (p<0.01). The mean doses and levels of Cy-A however did not change significantly during the three-month investigation period in the two groups and and the bioequivalence of the two preparations was evident. Conversion from Consupren sol. to Consupren S capsules is not associated with the risk of rejection or undesirable effects. It can be implemented at a ratio of 1:1 or 1: the closest dose divisible by 25 (the smallest capsules are 25 mg) and after conversion a check-up or possible modification of the dose is necessary.