Two adult patients receiving total parenteral nutrition on a long-term home basis presented with severe loss of hair. Both patients had extensive gut resection, consumed no biotin orally and received no biotin parenterally. Supplementation with Berroca-C, one ampule containing 200 micrograms biotin per day resulted in gradual regrowth of healthy hair. The patients now receive a parenteral solution containing biotin and have shown no recurrence of alopecia. It is suggested that biotin deficiency can occur in the adult when no preformed biotin is provided to the body and the contribution of this vitamin from intestinal microbial biosynthesis is compromised.