OBJECTIVES: Nausea and vomiting of pregnancy (NVP) is the most common medical condition in pregnancy affecting an estimated 80% (50%–90%) of all pregnant women. Even with mild symptoms, NVP generates costs to society, patients and the health care system, and reduces quality of life. However, its costs are largely unknown. We estimated the total cost per woman-week associated with the onset of NVP in Canada, stratified by the self-reported severity (mild, moderate, severe) from the perspectives of society, Ministry of Health and Long Term Care (MoH), and patients. METHODS: Data were collected from 139 pregnant women, who called the Motherisk Program at the Hospital for Sick Children in Toronto. Motherisk is a teratology information and counseling service for all questions related to pregnancy. We collected the information about resource utilization for direct costs (drugs, physicians, hospitalizations) and indirect costs by telephone interviews. Costing was conducted with Ontario price lists and fee schedules. Indirect costs were calculated using the human capital approach and included absences from work and/or usual activities as well as reduced productivity at work. RESULTS: From the societal perspective, the costs per woman-week were $124, $334 And $610 for mild, moderate and severe NVP, respectively. From the MoH perspective, the costs were $4, $36, and $87, respectively. From the patient perspective, costs per woman-week were $110, $253 and $375, respectively. Costs from all perspectives increased with increasing NVP severity. Lost productivity constituted the largest cost component. CONCLUSIONS: NVP in Canada is associated with substantial costs to patients, society and the MoH. Indirect costs were in all cases higher than direct costs.