The effects of the H-histamine blocker tripelennamine (Trp) on blood pressure, heart rate, ECG pattern, serum sodium, potassium and calcium levels as well as its effect on serum GOT and GPT, creatinine and urea levels were investigated, when administered intravenously (i.v.) and intracerbroventricular (i.c.v.), in a trial to compare between these two routes. Trp (2.5 mg/kg) i.v. and i.c.v. caused a significant long lasting rise in blood pressure, no significant difference occurred between i.v. and i.c.v. data at P0.01. In conclusion the route of administration may play a role in the effect induced by Trp The ECG changes produced by Trp may be related to electrolyte imbalance caused by this drug. Trp alters the liver function in the form of increased serum transaminases and changes the renal function as shown by increased serum urea level. These findings need more human studies in order to be considered when applying such therapy on man.