Background/Aims: In patients with chronic kidney disease (CKD) receiving adequate erythropoietin therapy, the ideal dose of nandrolone decanoate (ND) to enhance muscle mass is not known. Methods: In this phase II dose-finding study, 54 patients with CKD stage 5 were randomized to either low, medium or high doses of ND (50, 100 or 200 mg/week for 24 weeks, respectively, in males; doses halved in females), while 7 patients acted as non-randomized controls. The primary outcome measure was appendicular lean mass (ALM) by dual-energy X-ray absorptiometry. Fluid overload (hydration of the fat-free mass) and indicators of physical functioning were secondary measures. Harms were also recorded. Data were analysed using Quade’s (1967) non-parametric analysis of covariance. Results: ND increased ALM in a dose-responsive manner (change scores = 0.3 ± 0.3 vs. 0.8 ± 0.3 vs. 1.5 ± 0.5 vs. 2.1 ± 0.4 kg, control vs. low vs. medium vs. high dose groups, respectively, p < 0.001) with no increases in fluid overload but no consistent effect on physical functioning. The highest dose of ND (100 mg/week) was intolerable in females because of virilizing effects. Conclusion: If goals of future studies are to improve body composition, dosing of ND up to 200 mg/week in males and 50 mg/week in females should be investigated. However, to realize improvements in physical functioning, future phase III trials of ND may require additional interventions such as exercise training.