Background/Objective: To clarify the state of different immunologic factors in patients with acute rheumatic fever (ARF) and rheumatic heart disease (RHD) compared to healthy individuals.Patients and Methods: Patients with ARF (#21), patients with RHD six months after the onset of ARF (#19), and healthy children from the same age group with normal physical examination and no history of pharyngitis during the previous month as the control group (#20) were studied. All patients were evaluated and followed for the presence and the severity of carditis, heart failure, and valvular involvement with echocardiography. Antistreptolysin-O (ASO) titer, erythrocyte sedimentation rate (ESR), serum complements C3 and C4, immunoglobins IgA, IgM, and IgG, IgM Rheumatoid Factor (RF), IgM and IgG anti-cardiolipin antibody (ACLA), and IgM and IgG anti-M group A streptococcal protein (AMP) were compared.Results: There was a significant difference for IgG and IgM ACLA between groups (p=0.005 and p=0.0001, respectively). These results were shown to reflect the difference between patients with ARF and the other two groups. There was a significant difference for IgG AMP between ARF and RHD groups (p=0.05). There was a significant difference for IgM RF between ARF and RHD groups (p=0.05). There was a significant difference for serum IgG between groups (p=0.0005). This was shown to reflect a significant difference between patients with ARF and the two other groups. Serum IgG was significantly lower in patients with, than in patients without, aortic valve involvement (p=0.039). Similarly, Serum IgG was significantly lower in patients with pericardial effusion (p=0.013).Conclusion: There are significant differences for IgG and IgM ACLA and IgG AMP and serum IgG levels and IgM RF between ARF patients and the other two groups. Whether IgG has a “protective effect” in patients with ARF preventing them from developing pericardial effusion, aortic valve involvement, or other complications is a notable question that must be answered.