Undifferentiated spondyloarthropathy (uSpA) is a nonspecific form of spondyloarthropathy where nonsteroidal anti-inflammatory drugs (NSAIDs) and disease-modifying anti-rheumatic drugs are still mainstay of treatment. We evaluated the efficacy and adverse effect profile of pamidronate, in uSpA patients refractory to NSAIDs therapy. A case series of 87 patients fulfilling the modified Amor criteria for the diagnosis of uSpA, having active disease even after 3-month continuous therapy with two NSAIDs, were selected. Active disease was defined as a VAS score >50 in a scale of 0-100 in 3 out of four following parameters: patients' global assessment, pain, BASFI and BASDAI morning stiffness. Sixty-six patients among those were administered monthly pamidronate infusion (60 mg over 4 h in 500 ml of normal saline) for 6 months. Other 21 patients (placebo group) transfused with normal saline. Treatment outcome was assessed by comparing baseline and 6 months value of BASDAI, BASFI, BASMI, BAS-G, CRP and ESR in both groups and improvement by ASAS-20 and BASDAI-50. Among the 66 patients, 48 patients (72.73%) achieved ASAS-20 and 42 patients (63.64%) achieved BASDAI-50 response. Among the treatment group, mean ESR, CRP, BASDAI, BASFI, BAS-G and BASAMI reduced by 54.81 mm/h (64.95%), 3.94 mg/l (43.3%), 3.74 (48.38%), 3.73 (49.40%), 4.47 (58.97%) and 4.28 (58.15%), respectively, after treatment, whereas in placebo group, increased by 5.48 mm/h (6.34%), 0.34 mg/l (3.77%), 0.24 (3.02%), 0.45 (6.03%), 0.05 (0.67%) and 0.52 (7.13%), respectively, after 6 months. Intravenous pamidronate has very good efficacy for the treatment of uSpA.