Systemic activity of the intranasal glucocorticosteroid budesonide administered once daily from a dry-powder inhaler (Turbuhaler) was assessed by knemometry. Lower leg length was measured weekly in 38 children aged 7-15 (mean 11.3) years with allergic or perennial rhinitis. The design was a randomized, double-blind, parallel-group study. After 4 weeks' run-in, the children were allocated to 4 weeks' treatment with either budesonide 200 or 400 micrograms or placebo. Fourteen children in the budesonide 200-micrograms group, 13 in the 400-micrograms group, and 10 in the placebo group completed the study. In the placebo and budesonide 200-micrograms groups, growth velocities during run-in (0.36 and 0.28 mm/week, respectively) and treatment periods (0.34 and 0.27 mm/week, respectively) were almost identical. In the budesonide 400-micrograms group (run-in: 0.40 mm/week), a nonsignificant reduction in mean growth velocity of 0.18 mm/week was seen (P = 0.11). There were no statistically significant differences among the run-in mean lower leg growth velocities (F = 1.12; P = 0.34), among growth velocities during treatment (F = 1.10; P = 0.34), or among the run-in and treatment growth velocities in the three groups (F = 1.19; P = 0.32). These results provide good evidence that systemic activity is low in children with allergic or perennial rhinitis treated with once daily budesonide in doses of 200- and 400-micrograms administered intranasally from a dry-powder inhaler.