In this paper, the authors deal with problems associated with software product quality improvement activities. Software now-a-days is a part of different information systems and therefore participates in functioning of many sectors. Thus, directly or indirectly, its quality may affect performance of the whole industry. In the information technology sector a lot of attention is paid to software quality assurance. But, as it is not feasible to develop a program that does not contain errors, methods and techniques of software quality improvement are still being developed intensively. Based on years of experience in IT companies, the paper discusses quality improvement activities that were successfully implemented in practice in development processes.