We studied knowledge of nutritional needs during pregnancy and lactation in 150 pregnant Saudi women at three primary health care centers in Riyadh, Saudi Arabia. We used an interview schedule to collect data regarding the women's knowledge and to determine the effects of certain independent variables on the knowledge scores. Green et al.’s (1980) PRECEDE model provided the theorertical framework for the study. Descriptive statistics, t test, and chi‐square methods were used to analyze the data. The majority of the women had poor nutrition knowledge scores, with no significant differences among the three centers. A positive relationship was found between knowledge score and educational level. Negative relationships were found between knowledge score and number of pregnancies, number of deliveries, and number of living children. The findings have several implications for efforts to improve the health status of women in Saudi Arabia.