Almost 30-50% of patients on long-term therapy with glucocorticoids (GC), especially those affected by rheumatic diseases, develop glucocorticoid induced osteoporosis (GIOP) and osteoporosis-related fractures. To assess the effects of neridronate versus placebo on markers of bone resorption in rheumatic patients affected by GIOP (as defined by a T Score reduction > 2.5; mean BMD L2-L4), sixty-two female patients [age: 68.89 +/- 9.45 (mean +/- SD)] affected by different rheumatic diseases, like rheumatoid arthritis, polymyalgia rheumatica, Sjögren syndrome in treatment with a mean prednisone-equivalent daily dose of 6.44 +/- 2.4 mg/day, were enrolled in an open trial. The patients were divided in 2 groups: group A (26 patients) assuming daily calcium 1 g and vitamin D 800 UI and group B (36 patients) assuming daily calcium (1000 mg) and vitamin D (800 UI) and neridronate (25 mg im /30 days). The patients were evaluated for serum and urinary bone markers, basely (T0) and after 6 months of therapy (T6). After 6 months of therapy (T6), bone markers were significantly reduced in group B in respect to group A: OHPr - 41.64% (p < 0.001), D-Pyr - 34.96% (p < 0.001), NTX - 50.9% (p < 0.001). These preliminary data show that neridronate may be considered an useful agent for the treatment of GIOP in rheumatic patients.