The main goal of the paper was to identify contract mechanisms existing in transactions between producers’ organizations on the potato market and first buyers. The research was focused on contracts signed in 2014. The author has used the case study as the main research method, while the survey was conducted in the period March–May 2015 through the Computer Assisted Telephone Interview. 8 producers’ groups took part in the research (approx. 35% of the statistical population). In 2014 groups used to sell their outputs through contracts. The main first buyer of producers’ groups were processing plants.