Eleven rabbits were given bovine serum albumin i.v., in daily doses of 25 mg. Renal biopsy was performed on the 30th, 60th and 100th day of treatment and the specimens were subjected to light-, electron-microscopic and immunofluorescent studies, so as to follow up the dynamics of the glomerular process. Proteinuria and the serum creatinine and BUN levels were also measured. By the 100th day of treatment mesangioproliferative glomerulopathy had developed in 7, membranoproliferative glomerulopathy in 3 cases and membraneous glomerulopathy in 1 case. On the 30th day of treatment exudative glomerulopathy was demonstrable in the majority of the cases (in 9 animals). It is suggested that the earliest stage of the various glomerulopathies, regardless of their type, is marked by exudative lesions. The heaviest proteinuria was found in membraneous and membranoproliferative glomerulopathies. Changes in the serum creatinine and BUN levels indicative of a deteriorating renal function were noted in the membranoproliferative cases. The results are correlated with clinical observations of human glomerulopathies.