Acute (6.25 mg dm-3, exposure 36 h) and subacute (2.08 and 1.04 mg dm-3, exposure 1-8 weeks) levels of selenium caused periglomerular fibrosis accompanied with intrafiltration of blood cells in the capsular space. Proliferative glomerulonephritis as well as fragmentation and necrosis of cells of the renal tubule were also observed. However, no remarkable change was noted in fish exposed to a sublethal (0.625 mg dm-3) concentration of Se for 1-8 weeks.