Pheochromocytomas are rare tumors, mostly benign, but in 10% of cases malignant pheochromocytomas occur. According to the World Health Organization, the diagnosis of malignant pheochromocytomas is based on evidence of metastases to necromaphilic tissue away from tumor such as lymph nodes, bones, liver, lungs, brain and elsewhere. Based exclusively on histological parameters, it is not possible to diagnose malignancy although mitotic activity, cell atypia or vascular invasion are more expressed in malignant pheochromocytomas. Malignant pheochromocytomas grow relatively slowly and patients die from complications of the heart and blood vessels. The aim of this study was to present the characteristics of patients with malignant pheochromocytoma, treatment modalities and treatment outcome, and to compare them with the results of similar studies. Data of patients treated at the Department of Endocrinology of the Clinic for Internal Medicine of the Clinical Hospital Center Zagreb was used. Data was collected from the hospital database. Eight patients, 4 women and 4 men, were analyzed. The mean age at which diagnosis was made in women was 56.5 years and in men 49.4 years. In five patients (63.5%) the primary site of the tumor was the adrenal gland and in three (36.5%) tumor was found in chromaphilic tissue outside the adrenal gland (abdomen, thorax). The primary tumor (median size 7 cm) was surgically removed in all patients. Postoperatively, all were monitored (median follow-up was 61 months) and the median to metastases was 21 months. In three (37.5%) patients metastases were present at diagnosis. The most common site of metastases was the liver, followed by lymph nodes, bones and lungs, and the second line of treatment was performed with MIBG-131 radiotherapy in 7 (87.5%) patients and in 4 (50%) patients in combination with chemotherapy. During follow-up, two patients died of widespread malignancy. This study showed that only continuous postoperative monitoring of patients with pheochromocytoma or paraganglioma can detect metastatic disease. All of them underwent an individual clinical assessment of the development of the disease and were treated and monitored according to guidelines recognized worldwide.