The present study was carried out to examine the effect of orally administered T-3262, a new synthetic antibacterial agent, on the kidney of male rats with experimental nephropathy. These rats had been treated with single intramuscular injection of mercuric chloride (HgCl2, 3 mg/kg) or daily subcutaneous administration of puromycin-aminonucleoside (PAN, 15 mg/kg) for 11 days. T-3262 was administered orally to these pretreated rats at a dose of 1,000 mg/kg/day for 2 or 6 days. Twenty-four hours after the second or the sixth day of T-3262 administration, the kidneys of these rats disclosed similar biochemical and pathological findings as observed in the kidneys of the rats treated with HgCl2 alone. Thus, no T-3262-related alterations were demonstrated in renal functional test, kidney weight or histopathological examinations at a dose of 1,000 mg/kg of T-3262. The HgCl2-induced nephropathy was not enhanced by the oral administration of T-3262. Twenty-four hours after the second or the sixth day of T-3262 administration, the kidneys of the PAN-pretreated rats disclosed the biochemical and pathological findings largely similar to those with PAN-induced nephropathy. Enhancement of PAN-induced nephropathy by the oral administration of T-3262 was hardly evident.