The first half of this study describes the effects of acute splenectomy on epinephrine-induced ATL [acute tubular lesions] in the dog. Renal morphology and hematocrit were compared in 12 dogs without splenectomy (group I), 6 dogs with antecedent splenectomy (group II), and 7 dogs with antecedent splenectomy after splenic contraction was induced by topical application of epinephrine (group III). Splenectomy was performed in groups II and III 20-30 min prior to epinephrine infusion; all 3 groups received equal infusions (4 .mu.g/kg per min) for 6 h before the kidneys were harvested. ATL and renal congestion were consistently severe in group I but infrequent and less severe in groups II and III. The second half of this study describes the apparent protective effect of chronic (2 wk) splenectomy on epinephrine-induced ATL. Renal morphology and hematocrits were compared in 13 intact dogs (group IV) and 10 dogs splenectomized 2 wk before the epinephrine infusion (group V). The severity of the ATL and the degree of renal congestion were significantly less in the chronically splenectomized dogs. This chronic splenectomy was more protective than acute splenectomy. The mechanism of the renal protection afforded by acute and chronic splenectomy observed after epinephrine infusion remains unclear.