Dexamethasone (DEX) impairs growth and bone mineralisation in premature infants. Although tapered dose and constant dose are both used in clinical practice, it is not clear if the two dosing regimens induce similar alterations in growth and bone development. The aim of the study was to compare the effects of the two DEX treatment regimens on bone metabolism in piglets. Thirty five 7 to 8 day old male Yorkshire piglets were divided up as study 1: tapered dose group receiving DEX at 0.5, 0.3 and 0.2 mg/kg/d for 5 d each (n=8) and placebo control group (n=8); and study 2: constant dose group receiving DEX at 0.5 mg/kg/d for 10 d (n=8) and placebo control group (n=7). Body weight and length, femoral length, whole body bone mineral content (BMC) analyzed by DXA (Hologic QDR 1000W, Hologic Inc., Waltham, MA), plasma osteocalcin assayed by RIA (Incstar Corp., Stillwater, MN) and 24 hour urinary cross-linked N-telopeptide of type I collagen (NTx) assayed by ELISA(Osteomark, Seattle, WA) were measured. Urinary NTx was expressed as a ratio to urinary creatinine (NTx/Cr). At necropsy (d 15 for study 1 and d 11 for study 2), measures for DEX groups were calculated as Z-scores using respective control group results. The Z-scores were compared between the two DEX treatment groups. All measured parameters were similar at baseline. Cumulative DEX dose was similar between regimens. At the end of treatment, BMC, body weight and length and femoral length in the 2 DEX groups were significantly lower than control groups (p<0.0001) but did not differ between the two DEX regimens. Plasma osteocalcin was significantly (p<0.05) and similarly lower in both DEX groups compared to control groups. Z-scores for urinary NTx/Cr excretion in the tapered DEX group were lower (p<0.05) compared to the constant DEX group at necropsy. We conclude that despite differences in duration of DEX, both dosing regimens impair somatic growth and bone formation to a similar extent.