There is scarce and flawed data regarding vitamin D status in morbidly obese patients. More often than not, vitamin D deficits have been linked with bariatric surgery, not considering that the deficit may well precede surgery. Moreover, several pathophysiologic mechanism might explain, in part, vitamin D deficits. Conversely, the association between vitamin D deficits and secondary hyperparathyroidism in morbidly obese patients has been reported before and after bariatric surgery. Taking into account the elevated prevalence of vitamin D deficits in morbidly obese patients, its associated comorbidity, and the efficacy and low cost of its treatment to restore normal serum values of 25-OH-vitamin D, it seems advisable to recommend routine monitoring of serum calcium, phosphorus, and 25-OH-vitamin D levels in morbidly obese patients and to implement calcium and vitamin D supplementation whenever necessary.