Several previous investigators have reported an incidence of folic acid deficiency following gastric bypass surgery of up to 38%. Failure to encounter any folic acid deficiencies in our postoperative patients led us to discontinue follow-up folate studies for several years. However, due to repeated references to this deficiency in the literature, we re-instituted folate studies as part of the routine follow-up of our patients. Preoperative serum folate levels were obtained in 1,067 patients and preexisting deficiencies found in 63, an incidence of 6%. Of the 588 folate levels determined 1 to 10 years following gastric bypass, only six were less than 3.0 ng/di, an incidence of 1%. All patients were instructed preoperatively and postoperatively to take multivitamin/mineral supplements after gastric restrictive surgery, and were continually educated on their importance. In a bariatric surgery practice in which patients are instructed, reminded, encouraged and even badgered into taking postoperative vitamin/mineral supplements, folate deficiency should be a rarity. In such circumstances, folate deficiency may well act as a sensitive marker of non-compliance.