Vitamin D is an essential steroid involved in bone metabolism, cell growth, differentiation, and regulation of the minerals in the body. The main sources of this vital vitamin are adequate diet and photosynthesis in the skin. The aim of this study was to investigate the efficiency of vitamin D synthesis in 48 premenopausal women (14-44 years) in relation to three different types of dressing in summer. Women in the first group (Group I) dressed in a style which exposed the usual areas of the skin to sunlight; women in the second group (Group II wore traditional clothing with the skin of the hands and face uncovered, while the third group (Group III) dressed in traditional Islamic style, covering the whole body including hands and face. Serum 25OHD levels of Group I, Group II, and Group III were 56+/-41.3 nmol/l, 31.9+/-24.4 nmol/l, 9+/-5.7 nmol/l, respectively (Group I vs Group III, p<0.001; Group II vs Group III, p<0,03; Group I vs Group II, p>0.05). Vitamin D levels were low in 44 percent of the Group I and 60% of the Group II, which suggested that sun exposure of skin areas of hands and face may partially provide vitamin D synthesis, but may not be enough to eliminate vitamin D deficiency. All the patients in group III had vitamin D levels below normal. This study emphasizes the necessity of vitamin D fortification of food even in a sunny country where some people may not be exposed to sunlight because of inappropriate clothing or an indoor-life.