In this paper, we present a scalable FPGA design methodology for searching network packet payloads for a large number of patterns, including complex regular expressions. The efficiency of the technique enables a current-generation FPGA device to support pattern-matching at network rates from 1 Gbps to 100 Gbps and beyond. It offers flexible trade-offs between character capacity, throughput, and data bus width and rate. This allows the approach to be used in a wide range of devices from low-end home network appliances to high-end backbone routers. Suitable network applications for the FPGA pattern-matcher include firewalls, network intrusion detection, email virus scanning, and junk-email identification. In this work, we use a standard set of patterns from an intrusion detection system to demonstrate the performance and scalability of our design with a real-world application.