A sample of 871.3 patients/year was conformed by 205 postmenopausal women, aged 64.8 +/- 18.2 years (mean +/- SD), followed up during 51 +/- 12 months. All have osteoporosis, diagnosis assessed through radiological findings of at least one atraumatic fracture or vertebral crush ("severe osteoporosis" according to the new WHO classification). Each woman received 100 mg/day oral pamidronate (enteric coated soft gelatin capsules), half an hour before breakfast. Additional calcium and vitamin D were supplemented as follows: Total daily calcium = 1 g provided by diet and/or calcium carbonate. Vitamin D equivalent to 400-1200 IU/day. All patients were recommended to improve their physical activity, at least by walking exercise. Clinical examination radiological, bone mineral density (BMD) and biochemical studies were periodically performed. But, fracture indicence was the end-point of the study. Same was related to the 1,673 fall episodes recorded in the sample. In addition, height loss, lumbar BMD, proximal femur BMD, are also reported. Data has been cross-sectional collected in March 1995. All patients improved the symptomatology, specifically pain. This, and the good tolerability of the treatments proved to be considerably favorable for their compliance. Within the observation period, only 12 patients decreased their height (5.85%; mean = 0.85 cm; range = 0.5-2.0 cm). Lumbar spine BMD increased in 90% of 48 women. Mean gain after 2 years was 5.3 +/- 1.0% (p < 0.001). Proximal femur increased in 78% of other 32 women. Mean gain 6.3 +/- 0.7% (p < 0.001) after 2 years. A total of 78 new fractures were recorded, 47 vertebral crush, 29 forearm fractures and 2 hip fractures. Its incidence related to the fall episodes was of 2.8; 1.7 and 0.12% respectively. When compared with a historical estimated data, from an untreated population (Cummings SR et al, 1994), both, the total number of new fractures and the new hip fractures were significantly lower (p < 0.01) in our treated population than the reference data. Pamidronate, in oral doses of 100 mg/day, adequately supplemented with calcium and vitamin D, proved to be effective and a well tolerated therapy. The low rate of height's loss, BMD significant increases in subgroups of patients and the low rate of new fractures, strongly support the use of the compound to treat severe osteoporotic women. To our knowledge, this is the first time, that the new fracture incidence is related to the fall frequency reported in a bisphosphonate treated sample.