Abstract: Objective To analyze the clinical and pathological features of IgA nephropathy patients presenting with mild proteinuria and to describe risk factors associated with kidney injury.Methods The general and pathological data of patients with primary IgA nephropathy treated in our department from December 2015 to December 2016 were analyzed retrospectively. According to the 24-h total proteinuria, patients were divided into mild proteinuria group (<1 g/24h) and massive proteinuria group (≥ 1 g/24h), and the mild proteinuria group was divided into renal dysfunction subgroupeGFR<90 ml·min^-1·(1.73 m²)^-1 and normal renal function subgroupeGFR ≥ 90 ml·min^-1·(1.73 m²)^-1. The clinicopathological data of different groups and subgroups were compared and the risk factors of renal dysfunction were analyzed.Results Of 302 patients with primary IgA nephropathy enrolled in this study, there were 116 (38.41%) cases of mild proteinuria and 186 (61.59%) cases of massive proteinuria. The levels of serum creatinine, blood urea nitrogen and blood uric acid in patients with mild proteinuria were significantly lower than those in patients with massive proteinuria. Patients with CKD 1 stage and Lee's Ⅰ-Ⅱ grades made up the most part of the mild proteinuria group, with the difference being statistically significant (P<0.05). As compared with the normal renal function subgroup, patients were older, the percentage of hypertension and hyperuricemia was higher, and pathological injuries were severer, mainly in the Lee's grade Ⅲ in the renal injury subgroup (P<0.05). Multiple linear regression analysis indicated that age and level of serum uric acid were negatively correlated with eGFR of patients with mild proteinuria (P<0.05).Conclusions The pathological lesions of IgA nephropathy patients with mild proteinuria may be severe. Age and serum uric acid are independent risk factors for predicting renal dysfunction. Active intervention should be taken to improve the outcome of these patients.