PIP: This survey of 14 cultural groups in 10 countries provides data on the acceptability of changes in menstrual bleeding, the perceived characteristics of menstruation, and the relationship between menstrual beliefs and behavior. Results show that women are aware of the duration of their blood loss, the nature of menstrual blood, the physical discomforts associated with menstruation, but that they often confuse "duration" and "amount" of blood loss. This study also demonstrates that in order to have an accurate and useful definition of menstruation, it is necessary to delineate the separate elements of menstruation. Recommendations are made concerning information that should be provided by family planning personnel to their clients. Acceptable characteristics of new fertility regulating methods with regard to menstrual disturbances are discussed.