Integrating medical instruments with medical information systems becomes more and more important in healthcare industry. To make medical instruments without standard communication interface possess the capability of interoperating and sharing information with medical information systems, we developed a medical instrument integration gateway based on Integrating the Healthcare Enterprise Patient Care Device (IHE PCD) integration profiles in this research. The core component is an integration engine which is implemented according to integration profiles and Health Level Seven (HL7) messages defined in IHE PCD. Working with instrument specific Javascripts, the engine transforms medical instrument data into HL7 ORU message. This research enables medical instruments to interoperate and exchange medical data with information systems in a standardized way, and is valuable for medical instrument integration, especially for traditional instruments.