Approximately a quarter of the female workforce in Canada works shifts. Shift workers experience a misalignment between their endogenous circadian rhythms and their sleep/wake cycle, which can result in various health and psychosocial problems, including sleep disruptions, cardiovascular and gastrointestinal disorders, and effects on relationships and mood. Shift-working women also have several gender-specific health concerns and may be especially at risk for developing menstrual cycle irregularities, problems with reproductive health, and breast cancer. This article includes a theoretical background on circadian rhythms and clock genes, presents general problems of circadian misalignment, and discusses the specific issues associated with shift work as they pertain to women.