OBJECTIVES Until recently, two bisphosphonates, pamidronate (APD) and etidronate were available for clinical purposes. Contrary to etidronate, pamidronate was not extensively studied in osteoporosis. Therefore, we investigated the effect of cyclic intravenous APD treatment in postmenopausal osteoporosis. METHODS Parameters of bone remodelling and lumbar spine bone mineral density (BMDL) were assessed in 36 postmenopausal women with osteoporosis (BMDL t-score < -2.5). They received five courses of APD. Intervals between courses were defined according to the fasting urinary calcium excretion (UCa/Cr, mg/mg creatinine) which was measured before each APD course and every 2 weeks after the first treatment. The patients were retreated when UCa/Cr had reached baseline levels. Serum biochemical parameters and urinary hydroxyproline (UOHPro/Cr, mg/mg) were measured before each APD. RESULTS UCa/Cr decreased during 21-28 days after each course but UCa/Cr measured before APD infusion remained unchanged. UOHPro/Cr significantly fell after the third APD (P = 0.02). Serum calcium was however not modified. Parameters of bone remodelling decreased with time: bone-GLA protein (BGP) started to fall after the first APD (P = 0.0001) and continued to decrease until the fourth APD course, alkaline phosphatase (ALP) significantly decreased after the first APD (P = 0.005); intact PTH significantly increased at the fifth APD (P = 0.02). BMDL significantly increased after 1 year treatment: +2.9% of baseline value. CONCLUSIONS Cyclical pamidronate treatment of postmenopausal osteoprosis appeared to be effective in reducing bone turnover assessed by BGP, ALP and OHPro/Cr. This effect is followed by an increase in vertebral BMD.