This study was performed to assess the changes occurring in the field of urology with developments in outpatient surgery during a 5 year period. Using ICD‐9‐CM code, data for all urology procedures performed in the main operating rooms, day surgery and laser centre operating rooms of a large, general hospital were collected for the years 1987–92. A substitution index (SI) was determined as the ratio of the number of outpatients to the total number of procedures and expressed as a percentage. Changes in the SI reflects the degree to which emphasis has shifted from conventional inpatient to outpatient surgery. It was found that 26% of urology procedures were being performed as outpatients in 1987, and this increased to 42% by 1992. When broken down according to organ, the greatest increase in SI from 1987 to 1992 was for the kidney (57%) and the least, the penis (2%). with ureter, urethra, testes and scrotum all revealing intermediate, but significant, increases (27, 28 and 24% respectively). This paper thus demonstrates that, as in other fields, urology has experienced a marked increase in outpatient surgery. With developments in surgical and anaesthetic techniques, financial pressures, changing physician and patient attitudes and technological advances, further increases in urology outpatient care can be exp