The age of predilection for IgA nephropathy (IgAN) is generally younger than 30 years, but it sometimes occurs in people older than 60 years, and its characteristics remain unknown. We divided 600 patients with IgAN into three groups: senior group (n = 31, age ≥ 60 years); middle-aged group (n = 162, 40 years Q age Q 59 years); and young group (n = 407, 20 years Q age Q 39 years). We analyzed the clinical characteristics and histological background, prognosis of kidney disease and risk factors causing progression of kidney disease in these three groups. Patients in the advanced age group had significantly higher mean arterial pressure (MAP) and number of hypertensive disorders, significantly lower total serum protein, serum albumin and estimated glomerular filtration rate, and significantly higher blood urea nitrogen, urine protein and N-acetyl β-D-glucosidase than in the middle-aged and young age groups. Histological studies revealed that interstitial fibrosis and tubular epithelial cell atrophy and glomerular arteriosclerosis, as elucidated in the Oxford typing, were significantly more severe in patients in the senior group than in the young group. Renal survival by the Kaplan-Meier method was significantly lower in the advanced age group than in the middle-aged and young adult groups (22.9% for 19-year renal survival in the advanced age group and 69.2% and 84.9% for 20-year renal survival in the middle-aged and young adult groups, respectively, p<0.0001)< font>. Patients in the advanced age group who progressed to end-stage renal disease (ESRD) had higher mean arterial pressure and greater amounts of urinary protein compared with patients who did not progress to end-stage renal disease. IgAN in elderly patients is characterized by such glomerular disease and its concomitant diseases such as hypertension, dyslipidemia, and hyperuricemia that can cause lower renal function, massive proteinuria, severe interstitial changes, and small glomerular arteriosclerosis in elderly patients. The prognosis for IgA nephropathy in these patients is poor, with >70% of patients developing ESRD within 20 years.