The structural phase transition and metallization of the group II-VI compound zinc oxide (ZnO) is investigated through its band structure obtained using the full potential linearmuffin-tin orbital (FP-LMTO)method. The ground state properties and band gap values are compared with the experimental results. Under high pressure ZnO undergoes a first order structural phase transition from the ZnS structure (B3) to the NaCl structure (B1). The band structure, density of states (DOS) and total energy are computed as a function of reduced volume for both ZnS and NaCl phases. The values of pressure under reduced volume are calculated usingBirch-MurnaghanÂs equation of state.The pressure corresponding to structural phase transition from ZnS structure (B3) to the NaCl structure (B1) is 9 Gpa in ZnO. The metallization pressure PM is 95.3 GPa.