Nine normotensive healthy females received timolol 5 mg daily for a 4-day period and subsequently 20 mg daily for another 4-day period. None of the two dosages of timolol caused significant changes in serum uric acid or 24-h urinary fractional excretion of uric acid. Thus the increments of serum uric acid previously found in hypertensive patients is not likely to be caused by beta-adrenoceptor blockade per se.