Jordan is a sunny Middle Eastern country where no vitamin D fortification of milk is undertaken, and where women wear dress styles that cover the body to a variable extent. This may produce variable effects on vitamin D, parathyroid hormone and bone mineralization. The aim of the present study was to evaluate the vitamin D and parathyroid hormone levels in healthy young women of child-bearing age, and to examine the effects of dress style and season, in a survey of the effects of these parameters on vitamin D metabolism, and the possible bone mineralization consequences. One hundred and forty-six subjects (22 men, 124 women) were selected, according to established inclusion criteria. Of the women, 21 wore Western-type dress styles (group 1), 80 wore dress styles covering the whole body but the sparing face and hands (group 2) and 23 wore dress styles covering the whole body including the face and hands (group 3). The study was conducted in summer and winter. All volunteers underwent initial interviews, answered a food frequency questionnaire, and underwent essential laboratory tests (serum 25-hydroxyvitamin D (25(OH)D) by radioimmunoassay, and serum parathyroid hormone (PTH) by chemiluminescent enzyme immunoassay). The 25(OH) D levels in groups 2 and 3 were significantly lower than in the men (p<0.05 in both comparisons). No significant differences were noted between women wearing different dress styles. PTH levels were in the upper limits of normal but failed to show statistical differences between study groups. The prevalence of hypovitaminosis D was 62.3% in the study groups as a whole. Dress styles covering the whole body, totally or nearly totally, have adverse effects on 25(OH)D levels and may produce a state of secondary hyperparathyroidism on the long run. Although Jordan enjoys plenty of sunshine, these data are suggestive of widespread hypovitaminosis D in Jordan.