The aim of this study was to examine the effect of intranasal salmon calcitonin therapy on bone mineral density (BMD) in idiopathic male osteoporosis without vertebral fractures. We conducted a randomized, open label, controlled trial in 71 male patients (mean age 59 +/- 6 years) suffering from idiopathic osteoporosis (femoral neck T-score < -2.5) without vertebral deformity. Patients in the control group (n = 31) received 400 IU Vitamin D + 1000 mg elemental calcium daily while the treatment group (n = 40) received 400 IU Vitamin D, 1000 mg elemental calcium plus 200 IU calcitonin nasal spray daily during alternate months. The study period was 18 months. Compared to controls, nasal calcitonin was associated with significant increases in bone mineral density at the lumbar spine (+3.5 +/- (-4.3%) vs. +0.83 +/- 6.4%, P = 0.04) and the femoral neck (+3.2 +/- 3.9% vs. +0.68 +/- 5.7%, P = 0.004). No significant difference was observed at the radius between the treatment groups (+1.4 +/- 8.8% vs. +1.4 +/- 10.9%, P = 0.98). Treatment was well tolerated with no premature discontinuations or significant side effects compared to the control group. We conclude that 200 IU salmon calcitonin nasal spray used daily, intermittently proved to be an effective and safe therapy in male idiopathic osteoporosis.