BACKGROUND Premenstrual mood symptoms are considered common in women, but such prevailing attitudes are shaped by social expectations about gender, emotionality and hormonal influences. There are few prospective, community studies of women reporting mood data from all phases of the menstrual cycle (MC). We aimed (i) to analyze daily mood data over 6 months for MC phase cyclicity and (ii) to compare MC phase influences on a woman's daily mood with that attributable to key alternate explanatory variables (physical health, perceived stress and social support). METHODS A random sample of Canadian women aged 18-40 years collected mood and health data daily over 6 months, using telemetry, producing 395 complete MCs for analysis. RESULTS Only half the individual mood items showed any MC phase association; these links were either with the menses phase alone or the menses plus the premenstrual phase. With one exception, the association was not solely premenstrual. The menses-follicular-luteal MC division gave similar results. Less than 0.5% of the women's individual periodogram records for each mood item showed MC entrainment. Physical health, perceived stress and social support were much stronger predictors of mood (p < 0.0001 in each case) than MC phase. CONCLUSIONS The results of this study do not support the widespread idea of specific premenstrual dysphoria in women. Daily physical health status, perceived stress and social support explain daily mood better than MC phase.