The studies were aimed at the evaluation of the usefulness of non-invasive diagnostic methods including inquiry, clinical examination, transabdominal ultrasonography, cytologic examination of the urinary sediment, determination of blood serum concentrations of certain neoplastic markers, and urinalysis for early detection of neoplasms of the urinary tract and male genitals; and at the determination of the sensitivity and specificity of percutaneous ultrasonography combined with cytologic examination of the urinary sediment for detection of neoplasms of the kidneys and urinary tract, particularly of the urinary bladder. Urological examinations were performed in 300 workers occupationally exposed to oil derivatives. Neoplasms of the urinary tract and male genitals were detected in 37 (12.3%) workers. Neoplasms of the urinary bladder were found most frequently. They were diagnosed by non-invasive methods in 14 (4.7%) and verified clinically and histologically in 11 (3.7%) persons. The results seem to indicate the usefulness of non-invasive diagnostic methods for urological screening studies among occupational populations with increased risk of neoplasms of the urinary system and male genitals. The high sensitivity (93%) and high positive predictive coefficient (0.90) for the combination of transabdominal ultrasonography and cytological examination of the urinary sediment for detection of urinary system neoplasms seem to be tokens of their high diagnostic value and clinical usefulness.