Seed tubers of Irish potato varieties Dar, Oka, Bern, Pionier and Kolobrzeskie, received from Poland, were tested in the State of São Paulo with the best known Dutch variety, Eigenheimer. Eight trials were conducted in three different localities : Capão Bonito, Louveira and Indaiatuba. Varieties Kolobrzeskie and Pionier showed good resistance to both early and late blight. On the contrary, the varieties Eigenheimer and Oka were susceptible. Variety Bem has shown some physiological disorders through spotting of tuber flesh. Little tendency to such disorders was revealed by variety Pionier. The best yielding varieties were Eigenheimer, Oka, Kolobrzeskie, Bern, Pionier and Dar. Variety Kolobrzeskie and Bem yielded larger percentage of big-sized tubers;. Oka, Dar and Eigenheimer produced larger percentages of small-sized tubers.