Cardiovascular diseases are the leading cause of death in developed countries. Autoimmune diseases (AID) are in the top 10 causes of death in girls and woman below 64 years. The objective of this study was to investigate clinical outcomes in patients having AID subjected to open heart surgery. A prospective cohort study was carried out over 1-year in all consecutive patients (pts.) undergoing elective cardiac surgery. Primary endpoints defined as: length of hospital stay (LOS), rehospitalization rate and total costs. Over the study period, 72 adult patients were enrolled in: Group 1, n–36 patients with AID, and Group 2, n– 36 patients matched to have the same type of surgery. Patients were matched also using the EuroSCORE II (3.18 vs. 3.26%, p=0.893), gender (p=0.076) and age (62.2 vs. 60.9 years, p=0.702). With regard to demographic data, all p-values were not significant: LVEF (45.2 vs. 43.2%, p= 0.531), BMI (26.9 vs. 24.9, p=0.072), ACS (2.5 vs. 0.0%, p=1.0), hypertension (77.5 vs. 78.1%, p=1.0), hyperlipidemia (62.5 vs. 49.1%, p=0.277), DM (25 vs. 25%, p=1.0), smoking habits (17.5 vs. 31.3%, p=0.278), previous AMI (30.0 vs. 25.0%, p=0.837), family history (48.7 vs. 59.4, p=0.511), peripheral vascular diseases (30.0 vs. 15.6%, p=0.251), TIA (57.5 vs. 34.4%, p=0.086) except for allergic diseases (38.5 vs. 12.5%, p=0.029). After discharge 6/36 (16.6%) pts. have been readmitted in Group 1 (5.5% within 30 days, 16.2% within 90 days) and none in Group 2 (p<0.05). Patients in Group 1 spend less time at hospital after surgery (10.62 vs. 16.63 days, p=0.049) but LOS was not significantly different (20.7 vs. 23.2 days, p=0.449). Total expenses was higher in Group 2 (5554 vs. 7037€, p= 0.115) but not significantly. This study has shown that there is difference only in rehospitalization rate in patients with AID after open heart surgery.