The effects of inhaled budesonide (BUD) and oral prednisolone (PRED) on markers of bone turnover and adrenal function were compared in a randomized, double-blind, double-dummy, crossover study. Twelve healthy subjects were treated for one week with 0.8, 1.6 and 3.2 mg/day BUD and 5, 10 and 20 mg/day PRED, the three doses being given in ascending order. Plasma cortisol and adrenal cortical androgens showed a significantly decreasing trend with the increasing doses of both drugs, although PRED caused a significantly greater decrease than BUD. Osteoblast function, reflected by serum osteocalcin and alkaline phosphatase was significantly reduced by PRED, but BUD had a significantly different effect as it affected only osteocalcin. Urinary hydroxyproline/creatinine, a marker of bone resorption, was not changed by either drug. The average potency ratio for equivalent systemic effects was PRED:BUD 3.9:1. During short-term treatment at equivalent anti-asthmatic doses, BUD has significantly less effect on adrenal function and bone turnover than PRED, and it may carry less risk of bone complications during long-term treatment.