This study was undertaken to define the interrelationships of somatomedin, growth hormone, and an inhibitor of SM in protein-calorie malnutrition. Twenty-seven patients, eight to 60 months of age, were studied. Twenty-one well-nourished children acted as controls. SM was significantly depressed at Days 2 and 8 (p less than 0.01) but was not different from controls at Day 29 and 50. In ten out of 27 Day 2 samples and six out of 27 Day 8 samples an inhibitor was identified. When SM values were compared to simultaneous hGH levels, there was an inverse relationship. The low SM levels in the face of markedly elevated hGH levels suggests a functional block in the synthesis and/or release of SM.