The association between mood state and treatment outcome after In Vitro Fertilization/Embryo Transfer (IVF/ET) was assessed in a prospective sample of 330 women, of whom 113 were first time participants (inductees) and 217 were repeat cycle women (veterans). Initial evaluation of mood state indicated a significantly higher level of depression amongst veterans than inductees and a significantly greater proportion of veterans (25%) with clinically elevated depression scores compared with inductees (15%) and community norms (approx. 12%). Up to 12 months after initial assessment and after controlling for the number of treatment cycles, a significant difference was observed in the course of pregnancy over time between depressed and non-depressed women. Depressed women exhibited a lower pregnancy rate for the first treatment cycles than non-depressed women. The results and their implications are discussed.