The paper presents the relationship which determine the scale of financing investment with a financial surplus. The conducted study period covered years 2010-2014. The research investigated the relationship in the field of self-financing on the example of food processing companies. The main division criterion of companies in research were: Polish Classification of Economic Activities and classification to small and medium-sized enterprises. Based on the survey it was found that small and medium-sized enterprises were varied by the level of investment expenditure in relation to financial surplus. The greater part of the self-financing for investment purposes were allocate by medium-sized enterprises compared to small-sized. The strategy of self-financing changed with the increase in the scale of conducted performance by research companies.