A protocol is a program which controls, monitors and modifies the requests for laboratory services during the diagnostic work-up and/or monitoring of a patient. A protocol language and an OS/2 based system for the compilation, interpretation and execution of laboratory protocols written in this language is presented. The system is easily interfaced with any patient data base that supports the structured query language (SQL). A compiled protocol may be assigned to a patient and executed as specified in the protocol itself (regularly and/or when certain events such as test requests or arrival of results, occur). In the laboratory protocol language a patient's data are viewed as a set of test procedure groups each comprising data (request time, result, etc.) describing the status of one or more simultaneously made laboratory test requests. A pattern specification is a statement saying that a sequence of test procedure groups of specified types and ages is present in the data. Pattern specifications are linked to Boolean variables. If a pattern matching a pattern specification is found in the patient's database the corresponding Boolean variable is set equal to TRUE. The Boolean variables are utilized in the decision logic of the protocol.