BACKGROUND: Osteolytic bone destruction caused by increase of osteolytic activity is a major manifestation of multiple myeloma (MM). Pamidronate (3-amino-1-hydroxypropylidene)-1,1-bisphosphonate) inhibits osteoclastic activity and reduces bone resorption. METHODS: Since October 1995 the efficacy of pamidronate is evaluated in MM patients all receiving anti-myeloma chemotherapy acc. to VMCP/VBAP alternating regimen. 46 patients with stage III myeloma and osteolytic lesions were randomized to receive either pamidronate (Aredia; Novartis) 60 mg i.v. in 4-hour infusion monthly (n = 23) or chemotherapy alone (control group n = 23). Estimation of performance status, quality of life, pain score, analgesic consumption, serum calcium concentration and twenty four-hours Calcium excretion, urine Calcium/creatinine ratio is done at least once a month (before pamidronate administration) while X-ray skeletal survey--before treatment and then every six months. RESULTS: In the first months of treatment apparent reduction of bone pain occurred. Hypercalcaemia was revealed in 6 patients at entry into the study. In 5 of these patients pamidronate restored and maintained normocalcaemia for a median 6 months. In 3 patients an aggressive plasma cell proliferation was accompanied by reoccurrence of hypercalcaemia. At skeletal X-ray examination performed after 6 and 12 cycles of pamidronate and by comparing each of consecutive imaging with previous one the progression of osteolysis was respectively found in 67% and 39% of patients. In the control group corresponding figures were: 79% and 70%. The mean number of skeletal events (pathologic fracture, radiation to bone and spinal cord compression) per year was lower in the pamidronate group (1.82) than in control-patients (2.72), p < 0.013. The proportion of patients who developed skeletal event (excluding vertebral fractures) was lower in the pamidronate group -34% v 52%. Adverse events of pamidronate: hypocalcaemia (< 2 mmol/l) observed in 7 patients occurred in particular patients beginning from 2 to 7 days after drug administration. In 2 patients hypocalcaemia that appeared in 24 hours after drug infusion was accompanied by blood pressure decrease; in one case systolic blood pressure dropped up to 60 mmHg, in the other one--to 90 mmHg. Muscular pain and fever up to 39 degrees C (transient and self-limiting "influenza like syndrom") occurred in 5 patients, in two patients after several hours and in three other--after some dozens of hours from drug administration. In one case hypertransaminasaemia was observed. CONCLUSIONS: In the first year of treatment monthly intravenous pamidronate administration as an adjunct to chemotherapy in patients with advanced multiple myeloma with osteolysis is an efficient approach in prevention and treatment of hyperacalcaemia, hypercalciuria and bone pain. It also shows some preventive effect on bone lesion occurrence.