IgA nephropathy (IgAN) is the most common form of chronic glomerulonephritis with IgA deposits present mainly in the mesangial areas. We performed a 10-year retrospective case-control study of 71 patients with IgAN to evaluate the long-term effects and prognostic factors associated with tonsillectomy. Forty-one patients (19 males and 22 females) underwent tonsillectomy (Group A) and 30 patients (13 males and 17 females) did not (Group B). These patients were followed for more than 10 years after renal biopsy. The average age at initial renal biopsy was 29.78 years in Group A and 33.0 years in Group B. The average follow-up period was 13 years and 3 months in Group A, and 12 years and 7 months in Group B. Glomerular damage demonstrated on renal biopsy was more extensive in Group A than in Group B. Prognosis after 10 years of follow-up was compared between the two groups. The clinical remission rate was 24.4% in Group A and 13.3% in Group B, the stable renal function rate was 82.9% in Group A and 70.0% in Group B, and the renal survival rate was 95.1% in Group A and 73.3% in Group B. The renal survival rate in Group A was significantly higher than that in Group B (p &lt
0.05). Although evaluation of renal pathology based on renal biopsy was useful in predicting the long-term effects of tonsillectomy in IgAN patients, the results of tonsillar provocation tests were not.