The authors prospectively investigated 155 pregnant women, without a history of rheumatic disease who visited the Department of Obstetrics and Gynecology for routine antenatal care, to evaluate the prevalences and clinical features of arthralgia and arthritis in healthy pregnant women. Mean of the 155 subjects' ages was 31.8 +/- 3.8 (years, +/-SD). Arthralgia was found in 26 (16.7%) and arthritis in 15 (9.6%) pregnant women. Arthralgia or arthritis developed in the third trimester (28-40 weeks of gestation), except in one case (16 weeks of gestation). Most commonly involved joints were the proximal interphalangeal (n = 19, 12.2%). Rheumatoid factor and antinuclear antibody were negative in patients with arthritis. Ten women (6.8%) had persistent arthralgia for over 6 weeks, post-delivery. Four of them were followed up at Rheumatology Clinic and were diagnosed as having spondyloarthropathy (1), or unspecified arthralgia (3). In conclusion, arthralgia is common during pregnancy and most frequent in proximal interphalangeal joints.