This paper examines the impact of increased labour force participation in seasonal California agricultural employment of Mexican migrant women on maternal and infant health care. A hypothesis examined m this study is that inadequate prenatal, postpartum, and infant health care must be attributed to low participation rates in government programmes, infrequent use of medical services, and the large influence of custom on maternal and mfant health care. Survey evidence was based on a sample of 150 seasonal farm labour households in three major California counties. The evidence was compared with two other major California seasonal farm labour surveys in order to verify the hypothesis and to provtde information about the impact of the changing role of migrant females and famtlial health care. The study concludes that inadequate prenatal medical exams during pregnancy for those workingwomen may result in a higher incidence of birth-related problems; underpartic1pation m government programmes is strongly linked to cultural influences that associate pregnancy with a "normal" feature of those women's hves; low incidence of traditional methods of infant feeding (1.e., breastfeeding) is linked to the increased participation of those women in the seasonal agricultural work force; and custom plays a central role in postpartum and infant health care and, hence, has a direct impact on participation in available government health programmes.