What is the cost-effectiveness of gonadotrophins compared with clomiphene citrate in couples with unexplained subfertility undergoing intrauterine insemination (IUI) with ovarian stimulation under strict cancellation criteria?A cost-effectiveness analysis alongside a randomized controlled trial (RCT). Between July 2013 and March 2016, 738 couples were randomized to gonadotrophins (369) or clomiphene citrate (369) in a multicentre RCT in the Netherlands. The direct medical costs of both strategies were compared. Direct medical costs included costs of medication, cycle monitoring, insemination and, if applicable, pregnancy monitoring. Non-parametric bootstrap resampling was used to investigate the effect of uncertainty in estimates. The cost-effectiveness analysis was performed according to intention-to-treat. The incremental cost-effectiveness ratio (ICER) between gonadotrophins and clomiphene citrate for ongoing pregnancy and live birth was assessed.The mean costs per couple were €1534 for gonadotrophins and €1067 for clomiphene citrate (mean difference of €468; 95% confidence interval [CI] €464-472). As ongoing pregnancy rates were 31% in women allocated to gonadotrophins and 26% in women allocated to clomiphene citrate (relative risk 1.16, 95% CI 0.93-1.47), the ICER was €21,804 (95% CI €11,628-31,980) per additional ongoing pregnancy with gonadotrophins and €17,044 (95% CI €8998-25,090) per additional live birth with gonadotrophins.Gonadotrophins are more expensive compared with clomiphene citrate in couples with unexplained subfertility undergoing IUI with adherence to strict cancellation criteria, without being significantly more effective.