Aim: Gestational transient thyrotoxicosis was chosen to identify the effect of a non-immune thyrotoxicosis to vitamin D status during pregnancy. Material and Methods: Eighty-three pregnant women with gestational thyrotoxicosis and 28 healthy pregnant women were enrolled to the study. All the patients had thyroid ultrasound and were tested for hCG levels, thyroid function tests, TSH-receptor antibody, anti-thyroglobulin antibody, anti-thyroid peroxidase antibody, 25-hydroxyvitamin D, 1,25- dihydroxyvitamin D, calcium, phosphorus, erythrocyte sedimentation rate, C-reactive protein levels. Results: There was no statistical significance for age, gestational age, TRAb positivity, Anti-Tg positivity, ESR and CRP levels between the two groups. 25-hydroxyvitamin D levels are below the lower limit in both groups but 1,25-dihydroxyvitamin D levels of both groups were found within the normal range. Conclusion: Non-autoimmune thyrotoxicosis does not have any effect to the vitamin D status. The presence of nodules increases the risk of gestational thyrotoxicosis 2.67-fold. The level of 25- hydroxyvitamin D is low during pregnancy. Preserved level of 1,25-dihydroxyvitamin D maintains the balanced levels of calcium and phosphorus which have critical mission in bone metabolism.