The paper describes the potato parental line breeding programme developed in Poland from the 1960s. The aim of the programme was to create parental forms useful for speeding up the breeding of new potato varieties and getting higher efficiency in directed selection for desired traits. The programme introduced new sources of resistance and quality traits into the Polish breeding pool by conducting research and breeding of tetraploid and diploid parental lines. The programme had significant impact on potato breeding, with 72 Polish potato varieties originating from crossings involving parental lines. These varieties show higher levels of resistance to major pathogens of potato crops, including resistance to Potato virus Y and late blight in starch group. Besides the direct impact on potato breeding, the programme was the stimulus for developing studies focused on potato genotype.