Objective: The presence of autoantibodies against M-type phospholipase A2 receptor (anti-PLA2R) is a characteristic of id-iopathic membranous nephropathy (IMN). This study aimed to evaluate the presence, levels, and relationship of these an-tibodies 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 an-ti-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 ac-tive 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 pre-dictive 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 an-ti-PLA2R using IFT is a very sensitive and unique method.