Previously published data (J Bone Miner Res (2005); 20: 471) did not give evidence that the administration of the nitric oxide precursor L-arginine increases bone formation and decreases bone resorption in postmenopausal women. Data of this trial were reanalysed for putative effects of L-arginine on muscle mass and muscular function. Therefore, 11 females of the former study group (n=15; age 54.5+/-4.1 years; daily oral administration of 18 g L-arginine hydrochloride (equivalent of 14.2 g L-arginine) over 6 months) and 12 females of the control group (n=15; age 55.3+/-4.4 years; daily administration of 18 g dextrose over 6 months) were analysed for biomechanical parameters (MIGF, maximal isometric grip force; PJF, peak jump force; PJP, peak jump power) and for the cross-sectional muscle area (MA) and fat area (FA) at forearm and leg (calf) measured by peripheral quantitative computed tomography. The study was performed in a double-blind design. The assessment of muscular and biomechanical parameters was undertaken before and after 6 months of L-arginine versus placebo administration. L-arginine-supplemented females had a significant increase of PJF/kg in comparison with the control group. PJP/kg, MIGF, MA and FA were not significantly influenced by the administration of L-arginine. In conclusion, the administration of L-arginine increased maximal force in mechanographic analyses and may prevent a decline of muscle force in postmenopausal women.