A Cochrane review included 71 studies with a total of 10 520 subjects. Where interleukin 2 receptor antagonists (IL2Ra; basiliximab, daclizumab, or other) were compared with placebo (32 trials, 5 854 patients) graft loss including death with a functioning graft was reduced by 25% at six months (RR 0.75, 95% CI 0.58 to 0.98,16 trials) and one year (RR 0.75, 95% CI 0.62 to 0.90, 24 trials), but not beyond this. Acute rejection (AR) was significantly reduced at one year (RR 0.72, 95% CI 0.64 to 0.81, 14 trials)) and there was a reduction in cytomegalovirus (CMV) infection (13 studies: RR 0.81, 95% CI 0.68 to 0.97, 13 trials). Where IL2Ra were compared with other antibody therapy no significant differences in treatment effects were demonstrated, but adverse effects strongly favoured IL2Ra. There were no significant differences in outcomes according to cyclosporine or tacrolimus use, azathioprine or mycophenolate, or to the study populations baseline risk for acute rejection. There is no apparent difference between basiliximab and daclizumab. IL2Ra are as effective as other antibody therapies and with significantly fewer side effects.