© 2020 Turkish Society of Nephrology. All rights reserved.Objective: The presence of autoantibodies against M-type phospholipase A2 receptor (anti-PLA2R) is a characteristic of idiopathic membranous nephropathy (IMN). This study aimed to evaluate the presence, levels, and relationship of these antibodies with clinical parameters in idiopathic and secondary membranous nephropathy (MN) and IgA nephropathy (IgAN) in our country by indirect immunofluorescence (IFT) method. Materials and Methods: A total of 152 adult patients (97 IMN, 11 secondary MN, and 44 IgAN) were included. Serum anti-PLA2R levels were measured by IFT. All the kidney biopsies were evaluated in the same pathology laboratory. Results: A total of 54 of all patients with IMN were found to be anti-PLA2R-positive, but the patients with secondary MN and IgAN were anti-PLA2R-negative (p<0.001). At the time of diagnosis, when no treatment was administered yet, 42 patients were examined for anti-PLA2R, and 32 (76.1%) patients were found to be positive; 64.3% of the patients with currently active disease were anti-PLA2R-positive, and 82.6% of patients with partial or complete remissions were negative (p<0.001). In determining the disease activity, the sensitivity of anti-PLA2R was calculated as 73%, specificity as 82%, positive predictive value as 92%, and negative predictive value as 51%. Anti-PLA2R titration was found to be positively correlated with proteinuria. In multivariate analysis of the factors affecting the level of proteinuria, only the presence of anti-PLA2R was significant. Conclusion: Anti-PLA2R was the main target in most Turkish patients with IMN, and investigation of the presence of anti-PLA2R using IFT is a very sensitive and unique method.