Renal biopsy is usually performed as an in-patient procedure, with patients having to be confined to bed for about 24 hours of observation after the procedure. In an attempt to reduce avoidable hospital bills, renal biopsy as a day procedure was evaluated prospectively in 20 (8 M, 12 F) selected nephrotic patients who required renal biopsy to establish tissue diagnosis. They were all normotensive with no evidence of significant renal impairment and aged 21.5+/-2.9 years (range: 17-25). All biopsies were carried out in the morning and patients observed for a mean duration of 9.6+/-0.8 hours (range 8.5-10.5) before discharge, and seen again on outpatient basis within 48 hours of discharge from hospital. Adequate renal tissue was obtained from each of the patients, with a mean core length of 1.28+/-0.5 cm (0.5-1.75) and mean number of glomeruli per section of 10.1+/-4.8 (6-21). The mean number of passes made to obtain renal tissue was 1.7+/-0.4 (1-2). No macroscopic hematuria or significant complications occurred during the Post-OP observation period. It does appear that in carefully selected cases, renal biopsy can be safely performed as a day procedure without compromising adequacy of tissue obtained, while saving the enormous cost usually associated with prolonged observation period, Post-biopsy.