The purpose of this work is to study doses to patients undergoing interventional endourological procedures. The study was performed in a modern Clinic of Endourology and Shockwave Lithotripsy, equipped with two dedicated X-ray systems. The following information was recorded for each patient: type of the procedure, patient age, fluoroscopy time, number of images acquired and patient dose in air kerma-area product, P(KA), measured with KAP-meters integrated in the X-ray units. Eleven types of procedures were included. From the collected sample of 429 patients for all procedures, the mean fluoroscopy time varied between 0.2 and 4 min. The highest values of mean P(KA) 457 and 590 cGy cm(2) were found for percutaneous nephrolithotripsy and ureteroscopy, respectively. The mean values of P(KA) for rest of the procedures investigated were between 58 and 398 cGy cm(2). Individual patient doses varied between 2 and 2440 cGy cm(2) and fluoroscopy time--between 0.1 and 13.7 min. The first study in interventional endourology in Bulgaria demonstrated big variations in patient doses depending on the type and the complexity of procedure, operator's experience and exposure modes.