BACKGROUND The occurrence of analgesic nephropathy (AN) among renal replacement therapy patients in former Czechoslovakia is not known. Previous surveys were not based on representative samples and lacked uniform criteria for diagnosing the disease. METHODS Incidence of AN in former Czechoslovakia was investigated in patients commencing renal replacement therapy in 24 (1/3 of all) dialysis centres from 1 January to 31 December 1992. Patients showing an unclear renal diagnosis (n = 149) were investigated with an interview and renal imaging techniques. The diagnosis of AN was withheld or rejected on the base of recently published diagnostic criteria demonstrating that a decreased renal mass of both kidneys combined with bumpy contours and/or papillary calcifications had a high performance for diagnosing AN (Nephrol Dial Transplant 1992; 7: 479-486). RESULTS Based on the renal imaging criteria, AN was diagnosed in 30 of 328 registered patients, resulting in an AN incidence of 9.1% while the EDTA data only mentioned an incidence of 4.8% (period 1986-1989). The products most commonly abused were analgesic mixtures containing two analgesic substances combined with caffeine and/or codeine. CONCLUSIONS AN was found to be a common disease in the Czech and Slovak Republics. The disease was diagnosed using reliable renal imaging criteria.