Anticentromere antibodies (ACA) are useful in assessing and classifying patients with mild variant of systemic sclerosis called calcinosis, Raynaud's phenomenon, esophageal dysmotility, sclerodactyly, telangiectasias (CREST) syndrome. From their prognostic significance, we are interested in the prevalence and disease correlation in Thai patients. A total of 3,233 serum samples of patients with any musculoskeletal symptoms were sent for antinuclear antibody determination at Ramathibodi Immunology Laboratory Service between the years 1998 and 2001. Forty sera (1.23%) were ACA positive. These sera were from 27 patients with autoimmune diseases and 13 with nonautoimmune diseases. Among autoimmune group, scleroderma was the most common diagnosis (33.3%) with limited sclerosis being the most frequent variant. The percentages of autoimmune disease were almost the same among the low-titer (1:40) and the high-titer (1:640) groups. The study suggests that the prevalence of ACA in Thai patients is low. The presence of ACA detected in patients with vague musculoskeletal symptoms does not suggest a diagnosis of CREST syndrome. Even high-titer ACA can be found in nonautoimmune diseases.