Background and Objectives. Valvular heart diseases are among the frequent causes of cardiac surgery. Some patients have a well-known rheumatic condition. Heart valves are fragile connective tissues which are vulnerable to any systemic autoimmune diseases. This study was designed to evaluate the frequency of rheumatological background in patients candidate for valvular heart surgery in Afshar Cardiovascular Center, Yazd, Iran. Methods. One hundred and twenty (120) patients candidate for valvular heart surgery were selected for this study. Careful history and physical examination were undertaken from rheumatological stand points. The most sensitive screening serologic tests were also assayed. Results. The result of this study showed that 53.3% were male and 46.6% were female with mean age of years old. 45.8% of the patients had history of nonmechanical joint disease, 14.2% had history of rheumatological conditions in their family, and 30% had history of constitutional symptoms. 29.8% had positive joint dysfunction findings in their physical examination while 25.8% had anemia of chronic disease. Positive Rheumatoid factor (RF), anticyclic citrullinated peptide (CCP, ACPA), C-reactive protein (CRP), antinuclear antibody (ANA), abnormal urine and elevated erythrocyte sedimentation rate (ESR) were 34, 2.5, 26.7, 4.2, 5, and 36.7%, respectively. Antineutrophil cytoplasmic antibody (ANCA) and antiphospholipid (APL) were positive in a few cases. Conclusion. The findings of this study show immunologic bases for most patients with valvular heart diseases candidate for surgery. Undifferentiated connective tissue diseases may play an important role in the pathophysiology of valvular damage.