Information useful in estimating the occupational fluoride hazard to pregnant women is scanty. Fluoride excretion and balances were determined in 18 young women--seven who were not pregnant, six in early pregnancy (second quarter), and five in late pregnancy (fourth quarter)--over a 20-day period under confined metabolic conditions. The total fluoride intake averaged 1.35 mg/day (0.35 mg from the diet, 1 mg from a mineral capsule). Urinary fluoride excretion levels for the three groups were similar and averaged 0.95, 1.03, and 1.15 mg/day, respectively. On the average, 88% of the total fluoride excreted was in the urine and the remainder in the feces. With few exceptions, the women in each group demonstrated small positive balances; the averages were +0.19, +0.16, and +0.14 mg/day, respectively. The differences were small and not statistically significant (p greater than 0.1). These data indicate that fluoride metabolism is not markedly altered during the course of pregnancy.