The chapter presents the results of the research on the attempt to reduce the risks occurring during the execution of construction works. For example, a large construction project was selected. Attempts to reduce the risk were made by introducing the author's method of elaborating research results. This method was concerned with the classification, analysis and evaluation of observed irregularities on the site and in subcontractors. During the research carried out, the general contractor carried out finishing works with more than 50 subcontractors. These companies employed around 600 employees in the period under review. The study was conducted for two months. About 400 abnormalities were observed. Each of the abnormalities was subjectively assessed. This was done in accordance with the three-step scale accepted by the authors. This scale were established according to the harm that the observed irregularities could cause among employees or the environment. Then, due to their nature, these abnormalities were divided into 16 groups. Three indicators have been developed for the evaluation: the incidence of irregularities, the irregularity index for the whole construction, the percentage of irregularities for the whole construction. With the input data prepared and the indicators developed, numerical differences in the approach of individual companies to the problem of occupational safety, as well as the distribution of the significance of individual irregularities in the whole construction, are presented. The adopted methods have been developed in such a way that they can be used to investigate safety issues on other constructions with the help of subcontractors. Research shows that using appropriate occupational safety management policy, you can effectively improve the safety of Polish construction.