"Failure to thrive" is a general term that refers to an impairment of growth. The term may be used to cover all types of growth retardation or more specifically to refer to growth impairment that is associated with developmental delay and disorders of affect that are related to environmental deprivation. Failure to thrive is often included among the larger categories of child neglect, but the condition may be present whether or not neglect is involved. If small stature is used as the criterion for failure to thrive, then the statistics regarding the etiology of the growth impairment vary with the institution reporting the data. Children with failure to thrive (FTT) may present for medical care in a number of ways. Children may be referred for an evaluation when growth retardation is detected during a visit to a community agency or to an emergency department for an unrelated complaint. The unifying finding is that the child is too small. FTT is related to inadequate nutritional intake to assure appropriate growth. In children with organic FTT, there may be decreased appetite secondary to the underlying medical condition or to medications that the child is taking. Nutrition may also be lost through the improper functioning of the gastrointestinal tract. There are four major categories of the differential diagnosis for growth-impaired infant: small at birth, selective underweight, familial short stature, and constitutional delay in growth. Evaluation for FTT should include a full medical history, a thorough physical examination that encompasses an assessment of the growth parameters, laboratory tests, and imaging studies. Case management should include the addressing of specific medical problems and nutritional remedies. The prognosis with FTT is variable but can be good with the appropriate intervention. A case vignette with follow-up questions is presented. 5 references