A related commentary discusses this research. Optimal sex hormone-replacement therapy for women with CAIS who have had gonadectomy is controversial. Notwithstanding the diligence in executing this double-blind, randomised, crossover clinical trial, the study sample was small (The rarity of CAIS limits the sample size) and adjustments for multiple comparisons were not made, increasing the likelihood of type-1 errors. There are good reasons to be cautious about assuming that the hormone-replacement regimen alone was responsible for the increase in sexual desire. Mental health and sexual function are multifactorially determined, and problems are prevalent in the general population. Focusing on the hormone-replacement regimen alone is unlikely to yield the hoped-for psychological and psychosexual benefits. Optimal clinical service for girls and women with CAIS necessitates a balance between medical and psychological interventions that promote both physical health and wellbeing