Implementation of comprehensive internal quality control programmes and participation in external quality assessment schemes to monitor analytical performance of laboratory tests have been widely accepted as an essential and integral part of good laboratory practice. As these programmes involve a great deal of repetitive statistical calculations and graphic presentation of data on quality control materials, many laboratories and practically all organisers of inter-laboratory quality assessment schemes increasingly rely on computers to handle the burdensome processing of data and to provide timely feedback in a manner that is easily understood and readily interpreted by analytical staff. However, in spite of the best effort to ensure reliable analytical performance, spurious and misleading results can still occur as a result of non-analytical errors which are not readily detected by methods designed to monitor the quality of analytical process. The use of sophisticated computer system has enabled our laboratory to check for the existence of some of these errors. This paper describes the application of computers in a variety of internal and external quality assessment programmes and demonstrates the usefulness of retrieving patients' cumulative test results and at the same time performing delta or percentage difference checks on such data in the detection of non-analytical errors and unexpected variations in results. The role of the computer in minimising transcription errors, reducing turn-around time of testing and reporting, as well as improving the quality of laboratory reports is also mentioned.