Abstract: An ion selective electrode for chlorpheniramine (CP) was studied. The PVC(polyvinyl chloride)matrix membrane was prepared by the CP-tetraphenylborate salt, dibutyl phthalate and 10% PVC-tetrahydrofuran solution in weight ratio of 0.007:0.69:3.0. The CP ion electrode shows Nernstian range from 1×10-2 to 1×10^-5M in the pH range of 5～7, with an average slope of 56.0±0.1 mV/decade. Paracetamol (4-acetamidophenol), aminopyrine, caffeine, moroxydine, sodium benzoate etc do not interfere, whereas phenergan (promethazine) ion interferes. The electrode is useful as an indicator for the precipitation titration of CP and some of its preparations with sodium tetraphenylborate.