Between 2014 and 2016 the number of foreigners on the Polish labour market increased by over 300 per cent. They were mainly Ukrainian citizens taking up seasonal employment on the basis of the so-called ‘simplified system’. According to the literature, such a large increase in labour immigration in a short period of time may be an important factor in the growth of unemployment and the reduction of the employment rate of natives. The main purpose of this text is to show the correlation between the increase in the employment of foreigners in Poland and to determine whether or not this has had an impact on the deterioration of the state of the labour market. For this purpose, data from the Central Statistical Office and the Polish Ministry of Family, Labour and Social Policy were collected. As a result of our analysis, it was found that the significant increase in the presence of foreigners on the Polish labour market, which the country has faced in recent years, was not correlated with the rise in unemployment, the increase in the rate of economic inactivity and the availability of seasonal jobs. On this basis, we can state that the increase in the supply of foreigners on the Polish labour market, compared to other factors influencing it, was weak enough for the negative effects of the increased employment of foreigners to not occur.