Aim: Indices related to blood parameters that indicate inflammation have recently started to be used in determining prognosis for many diseases. Visceral involvement is the most important factor affecting prognosis in immunoglobulin A vasculitis (IgAV). In this study, we sought to explore the value of the systemic immune-inflammation index (SII) and the C-reactive protein-to-albumin ratio (CAR) in predicting visceral involvement in IgAV. Material and Method: Patients diagnosed with IgAV who had gastrointestinal, renal, testicular, or central nervous system involvement were considered patients with visceral involvement. All patients with IgAV were divided into two groups, those with and without visceral involvement. The effect of SII and CAR in predicting visceral involvement was evaluated by logistic regression analysis. Results: We found that in the summertime, the percentage of patients with visceral involvement was significantly higher than those without visceral involvement (p=0.010). The rates of the recurrence of the disease, arthralgia, arthritis, and fever were significantly greater in those with visceral involvement (p=0.032, p