The authors attempted to classify panic disorders into four types according to a clinical course and accompanying neurotic or depressive symptoms. The characteristics of each type are as follows; type I: a single panic attack is the only symptom, type II: only panic attacks occur frequently without any accompanying neurotic or depressive symptoms, type III: a recurrence of panic attacks and the gradual development of neurotic symptoms, such as anticipatory anxiety, generalized anxiety, agoraphobia, or hypochondriasis, type IV: depressive symptoms develop in the course of recurring panic attacks. Type IV is further divided into three subtypes. Type IV-1: depressive symptoms develop secondary to panic attacks and major depression later coexists with panic disorder. Type IV-2: panic disorder continuously changed into major depression. Type IV-3: panic attacks and depressive symptoms are seen independently. The most common types are type III and type IV-1, and seem to be a core group of the panic disorder. Typical cases of each type are presented and underlying psychopathology is discussed.