The relationship between glomerular sclerosis and hyaline arteriolosclerosis (HA) or tubulo-interstitial (T-I) change was investigated in 66 patients with IgA glomerulonephropathy (IgA-GN) and in 12 patients with idiopathic focal segmental glomerulosclerosis (FGS). More than a 10% incidence of global sclerosis was noted in 15 patients with IgA-GN and in 9 patients with FGS. There was no significant discrepancy of age between patients with IgA-GN and those with FGS (IgA-GN: 37.5 +/- 12.5; FGS: 35.7 +/- 10.3). In patients with IgA-GN, 7 out of 15 were HA-positive (46.7%), whereas in patients with FGS, 7 out of 9 were HA-positive (77.8%). However, a close correlation was observed between glomerular sclerosis and T-I change only in patients with IgA-GN (r = 0.82; p less than 0.001). The results suggested that in the case of IgA-GN, T-I change was related to the prognosis of glomerular sclerosis. In addition, it is assumed that a possible correlation exists between FGS and HA.