Most pheochromocytomas can be cured by resection. In view of the unfavourable prognosis for surgical therapy in cases of late tumour detection and malignant tumours, the aim of the present study is to differentiate between typical signs and symptoms of malignant versus benign pheochromocytomas. We investigated the records of 133 patients retrospectively (1967-1998). In cases of benign tumours (104 of 133, mean age 42+/-15.8 years) tumour size was 5.9+/-3.4 cm, and history was 47.4+/-75.4 months. 7.7% of the tumours were extraadrenal, and 77% had paroxysmal manifestations. The other 29 patients (mean age: 39.2+/-21.9 years) had malignant lesions (tumour size: 9.4+/-5.9 cm (p=0.0022); history: 7.4+/-5.6 months (p=0.0137); extraadrenal: 24.1% (p=0.0219); paroxysmal: 37.9% (p=0.0012)). Symptoms of patients with benign tumours were hypertension (80%), headaches (42.3%), sweating (30.8%), tachycardia (26%) and pallor (24%) (Malignant: Hypertension 46%, p=0.0873; headaches 11%, p=0.0008; sweating 11%, p=0.0196; tachycardia 14%, p=0.1961 and pallor 0%, p=0.0010). Abdominal pain and dorsalgia occurred more frequently in malignant pheochromocytomas (26% versus 7%, p=0.0014). Unusually short histories and extraadrenal localization appear to be suspicious for malignancy. The "typical" clinical signs and symptoms occur more frequently in patients with benign tumours and can therefore be regarded as typical signs of benign pheochromocytomas.