To evaluate the prevalence of anti- citrullinated protein antibodies (ACPA) in patients with a variety of rheumatic diseases other than rheumatoid arthritis (RA).144 cases of rheumatic diseases other than rheumatoid arthritis (RA) over a period of 1 year were recruited after consenting and followed up for 2 years. Their serum samples were tested for ACPA.ACPA seropositivity of 9.03% was observed in rheumatic diseases other than RA.Whether ACPA seropositivity in non-RA rheumatic diseases indicates a false positive result or an overlap RA syndrome is a mystery yet unsolved. Long term follow ups of these patients will be required to understand the course of rheumatic diseases in relation to ACPA..