We conducted an open-label, prospective, randomized trial to assess the efficacy and safety of RANKL inhibition with denosumab to prevent the loss of BMD in the first year after kidney transplantation. Ninety kidney transplant recipients were randomized 1:1 two weeks after surgery to receive denosumab (60 mg at baseline and 6 months) or no treatment. After 12 months, total lumbar spine aBMD increased by 4.6% (95% CI 3.3-5.9%) in 46 patients in the denosumab group and decreased by -0.5% (95% CI -1.8-0.9%) in 44 patients in the control group (between-group difference 5.1% (95% CI 3.1-7.0%), P<0.0001). Denosumab also increased aBMD at the total hip by 1.9% (95% CI, 0.1 to 3.7%; P=0.035) over that in the control group at 12 months. HR-pQCT in a subgroup of 24 patients showed that denosumab increased vBMD at the distal tibia and radius (all P<0.05). Biomarkers of bone turnover (β-CTX, P1NP) markedly decreased with denosumab (all P<0.0001). Episodes of cystitis and asymptomatic hypocalcemia occurred more often with denosumab, whereas graft function, rate of rejections and incidence of opportunistic infections were similar. In conclusion, denosumab increased BMD in the first year after kidney transplantation but was associated with more frequent episodes of urinary tract infection. This article is protected by copyright. All rights reserved.