Infants with protein sensitive colitis fed a nutritionally complete free amino acid-based medical food will be evaluated for 42 days.

Inclusion Criteria:

• Less than or equal to 6 months of age
• 36-42 weeks gestational age at birth
• Singleton or Twin birth
• Diagnosed with protein sensitive colitis
• Negative stool culture at time of study entry
• No previous history of consuming free amino acid-based medical food
• Not receiving cisapride or steroids
• No vitamin mineral supplement administration during the study period with the exception of iron or fluoride
• No milk or soy products for the duration of the study