Journal of Research in Medical Sciences1735-199516520110515Pamidronate infusion improved two cases of intractable seronegative rheumatoid arthritis67866786ENMansourSalesiAssistant Professor, Department of Rheumatology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran. mansour1380@yahoo.comPeymanMottaghi2011021120110514Pamidronate is a bisphosphonate derivative that can inhibit bone resorption by actions on osteoclasts and increase bone density in spite of treatment with steroids. This drug has the anti-inflammatory effect by increase apoptosis of monocytes. 5-10 percent of rheumatoid arthritis patients is seronegative and may be resistant to conventional disease modifying anti rheumatic drugs (DMARDs). Intravenous (IV) pamidronate can be effective in disease control in seronegative rheumatoid arthritis. We report two cases of seronegative and drug resistant rheumatoid arthritis that favorably responds to pamidronate. Key words: Pamidronate, Seronegative, Rheumatoid Arthritis