TOWNES,1in 1965, reported a 6-week-old white male infant with chronic diarrhea, failure to gain weight, hypoproteinemia, and edema. The infant was unable to hydrolyze dietary protein due to a singular deficiency of pancreatic trypsinogen. The present report describes a second instance of this interesting defect. Report of a Case The patient is a 6-month-old white female infant, the product of an uneventful, full-term first pregnancy of a 24-year-old housewife. The infant was delivered without complication from a routine cephalic presentation and weighed 4,099 gm (9 lb). The neonatal course was complicated by an imperforate anus which was primarily repaired transabdominally on the second day of life. She remained hospitalized until 1 month of age, during which time several formula changes were instituted because of poor weight gain. She was discharged at 1 month of age on a regimen of soybean milk formula, weighing 3,485 gm (7.7 1b). At