A 54-year-old woman with short bowel syndrome was supported with home parenteral nutrition. Six months after receiving 2200 kcal/day of balanced home parenteral nutrition without biotin, she developed biotin deficiency with complete hair loss, eczematous dermatitis, waxy pallor, lethargy, and hypersthesias . Blood and urine samples were collected prior to treatment. Serum zinc was 64 micrograms/dl (nl 50-150 micrograms/dl), and the triene/tetraene ratio was 0.068 (nl 0.4), thereby ruling out zinc and essential fatty acid deficiencies. Serum biotin was 332 pg/ml (nl 520 +/- 220 pg/ml), and urine biotin was 5.22 ng/mg of creatinine (nl 4.3-95 with a mean of 30.2 ng/mg creatinine). The same parenteral nutrition regimen was contained and oral biotin was administered (10 mg/day). After 3 wk, serum and urine biotin levels were 650 pg/ml and 35.6 ng/mg creatinine, respectively. New hair growth was evident and all of her other symptoms resolved. Intravenous biotin was then provided (5 mg/day) for a month after which serum and urine biotin levels were 1316 pg/ml and 178 ng/mg creatine, respectively. The patient has been subsequently maintained on an intravenous multivitamin product containing 60 micrograms biotin per daily dose and remains free of signs and symptoms of biotin deficiency.