Objective: Our purpose was to provide a detailed description of patterns of nausea and vomiting of pregnancy. Study Design: A prospective study was performed with 160 women who provided daily recordings of frequency, duration, and severity of nausea and vomiting. Results: Seventy-four percent of women reported nausea lasting a mean of 34.6 days. “Morning sickness” occurred in only 1.8% of women, whereas 80% reported nausea lasting all day. Only 50% of women were relieved by 14 weeks’ gestation; 90% had relief by week 22. Data based on the McGill Nausea Questionnaire indicate that the nausea experienced by pregnant women is similar in character and intensity to the nausea experienced by patients undergoing cancer chemotherapy. Conclusions: Traditional teachings about nausea and vomiting of pregnancy are contradicted by our findings. Standardized tools for measuring the distribution, duration, and intensity of nausea are applicable to the study of nausea and vomiting of pregnancy and could be used in clinical trials to assess palliative measures. (Am J Obstet Gynecol 2000;182:931-7.)