The objective of this study was to evaluate the common effects of maternal vitamin D deficiency, various doses of vitamin D given to newborns and the effects of these on vitamin D status in early childhood. Seventy-eight pregnant women and 65 infants who were followed up in various health centers were included in the sudy. 25-hydroxyvitamin-D (25-OHvitD), calcium (Ca), phosphorus (P) and alkaline phosphatase levels were measured in blood samples drawn from pregnant women in the last trimester. Infants born to these mothers were given 400 or 800 IU of vitamin D subsequently at the start of the second week. 25-OHvitD, Ca, P and alkaline phosphatase levels of the 65 infants who were brought in for controls (May-September 2000) were measured and hand-wrist X-rays were evaluated. We analyzed the relationship between vitamin D status of the mothers and infants and socio-economic status; mothers' dressing habits (covered vs uncovered), educational level, and number of pregnancies; and sunlight exposure of the house. Covered as a dressing habit meant covering the hair and sometimes part of the face and wearing dresses that completely cover the arms and legs. In 40 infants who were breast-fed and received the recommended doses of vitamin D on a regular basis, the relationship between serum vitamin D levels and supplementation doses given was analyzed. Serum 25-OHvitD level of the mothers was 17.50 +/- 10.30 and 94.8% of the mothers had a 25-OHvitD level below 40 nmol/L (below 25 nmol/L in 79.5%). The risk factors associated with low maternal 25-OHvitD were low educational level (p = 0.042), insufficient intake of vitamin D within diet (p = 0.020) and "covered" dressing habits (p = 0.012). 25-OHvitD level of the infants was 83.70 +/- 53.70 nmol/L, and 24.6% of the infants had 25-OHvitD levels lower than 40 nmol/L. Risk factors for low 25-OHvitD levels in infants were a) not receiving recommended doses of vitamin D regularly (p = 0.002) and b) insufficient sunlight exposure of the house (p = 0.033). There was a pour but significant correlation between maternal vitamin D levels and infants' 25-OHvitD levels at four months (r = 0.365, p < 0.05). No significant correlation was found between 25-OHvitD levels and supplementation doses of vitamin D (19 infants were supplemented with 400 IU/day and 21 with 800 IU/day of vitamin D) (p = 0.873). Severe maternal vitamin D deficiency remains a commonly seen problem in Turkey. However, vitamin D deficiency can be prevented by supplementation of vitamin D to newborns (at least 400 IU). Supplementation of 800 IU vitamin D in the areas of maternal vitamin D deficiency has no greater benefits for the infants.