This study is carried out to investigate the sublethal (1/10th of predetermined LT50/96h) effect of Lead acetate on some biochemical parameters of an estuarine fish, Mystus cavasius (Ham.). The parameters measured were Glucose (mg/dl) and glycogen (mg. g–1 wet tissue) in the liver and muscle tissues over a period of 12 hours. The results of this work clearly indicated that lead induced significant elevated levels of blood glucose or Hyperglycemia was found in the treated groups than controls. Also, the lead caused depletions in the Glycogen content in liver and muscle tissues of M. cavasius. Significant decreases (P < 0.05) in glycogen levels were noticed in liver than the muscle tissue.