Abstract Computers as integral systems components determine the quality of work of operators in industrial production. This paper contributes to improving the design of man-machine systems by proposing a formal aid to human software requirements definition and design. First, the need for considering human requirements is stressed. Since technology is to be considered as ‘non-deterministic’, the designer is faced with a degree of freedom in his design decisions which can be and should be utilized for raising the quality of work of people operating computer-controlled man-machine systems. Then, a hierarchy of human quality criteria applicable for ergonomic judgement of work design measures is derived. Following the principle of prospective work design, these criteria must be considered as design goals just like technical and economic requirements. As a formal aid for making design decisions meeting these comprehensive requirements, the Requirements/Quality Criteria Matrix is proposed. Finally, this method of considering human requirements is illustrated by designing some man-machine interface features for operators of a hypothetical flexible manufacturing system.