This work elucidates the evolution of three generations of the laboratory information system in the National Taiwan University Hospital, which were respectively implemented in an IBM Series/1 mini-computer, a client/server and a plug-and-play HL7 interface engine environment respectively. The experience of using the HL7 healthcare information exchange in the hospital information system, laboratory information system, and automatic medical instruments over the past two decades are illustrated and discussed. The latest design challenge in developing intelligent laboratory information services is to organize effectively distributed and heterogeneous medical instruments through the message gateways. Such experiences had spread to some governmental information systems for different purposes in Taiwan; besides, the healthcare information exchange standard, software reuse mechanism, and application service provider adopted in developing the plug-and-play laboratory information system are also illustrated.