A case is described of manic-depressive variant syndrome of childhood in a ten-year-old boy. Children with manic-depressive variant syndrome frequently have signs and symptoms of hyperactivity and are often first seen by their pediatrician. The diagnoses of attention deficit disorder, organic mental disorder, borderline personality disorder, and childhood schizophrenia, are discussed with relation to their differentiation from the manic-depressive variant syndrome of childhood. The discussion further describes the early onset of symptoms in this boy and points out how a consideration of this diagnosis might be possible in early childhood, allowing for early inauguration of lithium therapy.