During an 8-year period, 163 consecutive patients with spinal crush fracture osteoporosis started a 5-year treatment with a combination of sodium fluoride (60 mg/day), calcium phosphate (45 mmol/day) and vitamin D2 (18,000 IU/day), and were followed in the outpatient clinic every 3 months. Fourty-three patients completed the 5-year treatment. Mean observation time was 2.8 years, totalling 460 patient-years. Fifty-one percent of the patients experienced joint-related (37%) or gastrointestinal (25%) side effects at one time or another. All side effects subsided after a median 6-week withdrawal of fluoride. Six percent of the patients withdrew from treatment due to side effects. Mean serum calcium values slightly decreased during treatment and no hypercalcemic episodes were seen. Urinary excretion of calcium did not change during treatment. No changes in renal, bone marrow or thyroid functions could be detected. The liver function might be slightly affected as indicated by minute increases in serum bilirubin and decreases in serum coagulation factors and albumin, but no other changes in liver function were observed.