Effect of fenvalerate on cell architecture, tissue biochemical parameters and its residual concentration was studied in broiler chicks following dermal application at 0.1 and 1% in ethanol once daily for 31 days. It did neither produce loss of body weight nor clinical signs of toxicity. Kidney contained maximal residue followed by heart, fat, liver and brain after 0.1%; and fat contained maximal residue followed by kidney, heart, liver and brain after 1% application. Fenvalerate (0.1%) increased the aspartate aminotransferase (AST) (except brain), alanine aminotransferase (ALT), alkaline phosphatase (AP), acid phosphatase (AcP) (only brain) activities, glycogen level (only liver) in liver, kidney, heart and brain tissues; and 1% increased the AST (except brain), ALT, AcP (except liver and kidney), AP (only heart), glycogen (only liver) and decreased AP (except heart), AcP (only kidney), cholesterol (except liver and heart), and acetylcholinesterase (AChE) (liver and brain) of liver, kidney, heart and brain tissue homogenates respectively. Histopathological examination in general showed aggregation of mononuclear cells in liver, around the kidney tubules and cardiac muscle fibre. In addition, fibrosis in the periportal area of liver, proliferation of ureter and tubular degeneration, and congestion of endocardial vessels were also observed. The intensity of cellular changes was more marked after 1% dermal application.