The influence of genotype, place and year of cultivation on the nitrates content in potato tubers is presented. The first experiment was carried out with 7 varieties in the years 1995 and 1996 originating from 3 different sites in Poland: Marianowo – brown soil, Głodowo and Seroczyn – podsolic and pseudopodsolic soil. The investigation showed the significant differences in nitrate content between soil types and seriously the influence of genotype and climatic factors during vegetation on nitrate level. Tubers grown up on the better soils in Marianowo had lower level of nitrates. During hot and dry vegetation weather the potato tubers accumulated more nitrate. The second experiment carried out in the years 1996-1999 in experimental field in Jadwisin has been found that date of harvest had affect on nitrate content. The tubers harvested in August (immature) had higher level of nitrate than mature ones.