In this paper, we propose a high performance elliptic curve cryptographic processor over GF(2^163). The proposed architecture is based on a modified Lopez-Dahab elliptic curve point multiplication algorithm and uses Gaussian normal basis (GNB) for GF(2^163) field arithmetic. To achieve a high throughput rates, we design two new word-level arithmetic units over GF(2^163) and derive a parallelized elliptic curve point doubling and point addition algorithm. We implement our design using Xilinx XC4VLX80 FPGA device which uses 24,263 slices and has a maximum frequency of 143MHz. Our design is roughly 4.8 times faster with 2 times increased hardware complexity compared with the previous hardware implementation. Therefore, the proposed architecture is well suited to elliptic curve cryptosystems requiring high throughput rates such as network processors and web servers.