The purpose of this paper is to provide empirical quantitative evidence concerning human capital in SMEs, the relationship between knowledge accumulation and firm size/firm human capital. This article provides analysis of the key findings of the survey which was conducted among 1308 small and medium sized enterprises in the private sector in Poland. The findings highlight the important role played by human capital in knowledge acquisition and performance of SMEs. The proportion of entrepreneurs who have achieved a tertiary education (38%) is almost 21% higher than that of the 24-to-64-year-olds. 29,3% of SMEs train their employees, but only 2,3% SMEs use advisory services of knowledge centers, and 5,5% of SMEs carry on marketing research. Human capital embodied in business owner has positive effect on propensity to train employees, use of advisory services and carrying on marketing research. There is also significant firm size effect that influences SME knowledge acquisition. The results indicate that development of knowledge can be affected by investments in human capital, and should be of interest to policy makers developing new strategies and policies to support the growth of SMEs in Poland.