Background: Up to now, there have been very few studies concerning delay issues in the treatment of breast cancer in Poland. The aim of the study was to determine the time and causes of delay in the treatment of women diagnosed with breast cancer and the importance of demographic and social factors on the occurrence of delays in the implementation of therapy. Material and Methods: The study was conducted in 2015–2016 in the Podkarpackie Oncology Centre in Brzozów for a group of 231 women. The time criterion of the delays in the treatment of women suffering from breast cancer was more than 1 month from the first oncological consultation to therapy initiation. The diagnostic poll method and medical documentation analysis were used. Research tools included a survey questionnaire and research protocol. The collected material was subjected to the statistical analysis using the χ² test. The values of p < 0.05 were considered statistically significant. Results: Delays were noted in 62.8% of the study participants and the mean delay time took 12.6 weeks. The main causes of the delays were: fear that the diagnosis would be confirmed, long waiting time for specialist investigations and their results, age, marital status and professional activity. No statistically significant correlation was found between profession, education level and the place of residence with therapy delays. Conclusions: Delays in the treatment of breast cancer patients were noted in the majority of study participants. A correlation was observed between the delays and chosen sociodemographic factors. Med Pr. 2019;70(1):89–98