Diffuse hyperpigmentation in the pediatric population is a rare condition with multiple causes. We present three cases of diffuse hyperpigmentation in infants, each with a different underlying diagnosis: primary adrenal insufficiency, familial glucocorticoid deficiency, and neonatal hemochromatosis. All three entities presented with diffuse hyperpigmentation in the neonatal-infantile period, along with systemic features and abnormal laboratory parameters. Early diagnosis and appropriate treatment are crucial for these conditions, as they can have significant health consequences.