261 patients who received a kidney transplant under cyclosporin-A immunosuppression were reviewed in order evaluate the benefits and the risks of renal graft biopsies. 240 graft biopsies were performed in 124 of the 261 patients. The biopsy diagnoses were 103x rejection, 90x cyclosporin-A toxicity, 8x acute tubular necrosis, 8x glomerulonephritis, 9x different biopsy results, and 12 cases of normal renal tissue. In 214 cases the clinical course was well explained by the biopsy result. The histological results led to therapeutical changes in 199 cases. 221 of the 240 biopsies were performed without any complications. There was only one biopsy with irreversible and there were 19 biopsies with reversible complications.