The purpose of this paper is to demonstrate the employment costs and advantages of employing a foreign labour force. The analysis was made based on the dual labour market theory, whereas employers were divided into employers of foreigners in occupations from the primary and secondary labour market.The analysis was based on 263 semi-structured interviews with employers from the Opolskie Voivodeship (Poland). The respondents were contacted in several ways. Firstly, the CAWI (Computer-Assisted Web Interview) and then PAPI (Paper & Pen Personal Interview) methods were used. The study showed that there is a significant statistical relationship between the labour market segment in which an employer hires a foreign employee, and the advantages gained by the employer. On the other hand, the study demonstrated no statistical relations between the labour market segment and the barriers for employing foreigners and their evaluation made by employers.