We investigated the effects of time-pressure stress on Raven's Standard Progressive Matrices performance in 64 low- and 64 high-trait anxious female subjects, tested either during premenstruation or menstruation. Based on previously reported associations between arousal/stress and intelligence test performance, we predicted that menstrual cycle variation would interact with stress-induced arousal/emotion and individual differences in reactions to aversive stimuli, as measured by trait anxiety. Our predictions were confirmed by Stress × Menstrual Phase and Trait Anxiety × Menstrual Phase interactions, which pointed to important moderating roles of stress and personality in menstrual cycle effects on cognitive performance. The results revealed that stress impaired performance during premenstruation, but improved it during menstruation; high trait anxiety impaired performance, irrespective of menstrual phase and only low trait anxiety was associated with an improvement in performance from premenstruation to menstruation phases of the cycle. The implications of our study for menstrual cycle and cognitive performance research is outlined.