The objective of the doctoral dissertation is to develop a Method of Quality Systems Application (QSA) that would promote application of knowledge incorporated in quality systems for management of small and medium mechanical engineering enterprises and enterprises of other branches. A method for the distribution of enterprises by size class in Latvia and mechanical engineering sector having certified quality management system according to ISO 9001 has been developed and results obtained. The set of questions have been developed and the amount of improvements after certification of quality management systems according to the requirements of ISO 9001 in SMEs of mechanical engineering in Latvia is assessed. The advanced manufacturing technologies most widely used in the enterprises of mechanical engineering in Latvia have been established. The new method of QSA and its implementation sequence are developed to conduct combined analysis of activities for the persons of the highest level. The mathematical prediction model for determination of the performance level has been developed. The recommendations are developed for the persons of the highest level of small and medium enterprises of mechanical engineering.