25 Hydroxycholecalciferol levels were measured in eight Beduin mothers in labor and in the cord blood of their infants, and compared with values in 42 Sephardi Israeli women in labor and the cord blood of their offspring. Beduin baby cord blood had a mean 25 hydroxycholecalciferol concentration of 3.78 ng/ml ± 3.22 (SD) being about half of their mothers' level in labor. Values in Sephardi women and cord blood were 3 times higher. PTH levels were lower and calcium concentrations were higher in cord blood (P<0.001) in both groups when compared to their mothers' blood. The relevance of these findings to the high incidence of infantile rickets and hypocalcemia in Beduin children is discussed.