In 3 open-label studies, the systemic bioavailability of budesonide and formoterol administered via pressurized metered-dose inhaler (pMDI) or dry powder inhaler (DPI) formulations was evaluated in asthma (24 children, 55 adults) or chronic obstructive pulmonary disease (COPD; n = 26) patients. Treatments were administered at doses high enough to estimate pharmacokinetic parameters reliably. Two of the studies included an experimental budesonide pMDI formulation. In study 1 (asthma, adults), budesonide area under the curve (AUC) was 32% and 31% lower and maximal budesonide concentration (C(max)) 45% and 56% lower after budesonide/formoterol pMDI and budesonide pMDI versus budesonide DPI. Formoterol AUC and C(max) were 13% and 39% lower after budesonide/formoterol pMDI versus formoterol DPI. In study 2 (asthma, children), budesonide AUC and C(max) were 27% and 41% lower after budesonide/formoterol pMDI versus budesonide DPI + formoterol DPI. In study 3 (COPD/asthma, adults), budesonide AUC and C(max) were similar and formoterol AUC and C(max) 18% and 22% greater after budesonide/formoterol pMDI versus budesonide pMDI + formoterol DPI (COPD). Budesonide and formoterol AUC were 12% and 15% higher in COPD versus asthma patients. In conclusion, systemic exposure generally is similar or lower with budesonide/formoterol pMDI versus combination therapy via separate DPIs or monotherapy and comparable between asthma and COPD patients.