OBJECTIVE: To assess which personality traits are associated with depressive and/or anxiety disorders in infertile women and men undergoing in vitro fertilization (IVF). DESIGN: Prospective study. SETTING: A university hospital in Sweden. POPULATION: A total of 856 eligible women and men, 428 couples, were approached to participate. Overall 643 (75.1%) subjects filled out the Swedish Universities Scales of Personality (SSP) questionnaire. The response rates were 323 women (75.5%) and 320 men (74.8%). METHODS: The SSP, a self-rating personality trait questionnaire, was used for evaluation. Main outcome measures. Personality traits associated with depression and/or anxiety disorders. RESULTS: Higher mean scores on all neuroticism-related personality traits were found in women and men with depressive and/or anxiety disorders compared to women and men with no diagnosis. High scores of neuroticism and a negative pregnancy test after IVF were associated with depressive and/or anxiety disorders among women. Among men, high scores of neuroticism and unexplained or male infertility factor were associated with depressive and/or anxiety disorders. High neuroticism scores were negatively associated with live birth (p < 0.05). CONCLUSION: High scores on neuroticism-related personality traits were associated with depressive and/or anxiety disorders in women and men undergoing IVF.