The problem of compliance and control in the treatment of diabetic patients is widely recognized. However, compliance research is contradictory and impractical as a basis for intervention to improve the patient's adherence to his medical regimen. Health beliefs may provide an opportunity to intervene to improve compliance and control of the disease. In this study we examined the health beliefs of 93 male diabetic patients and correlated their beliefs with behavioral and physiologic measures of compliance gathered at a follow-up interview. The belief in severity of illness related to compliance. Health beliefs were better predictors of metabolic control than compliance itself. The study suggests that improving attitudes about care may be a means of directly influencing control of the disease.