Abstract: This research was initiated with the aim at finding varieties of Potato that can respond to graded levels of NPK fertilizer and form of seed tuber. The treatments tested consist of four rates of NPK fertilizer (0, 300, 600 and 900 kg ha-1), two forms of seed tuber (whole and cut-tubers) and four varieties of Irish potato (Greta, Nicola, RC 767-2 and WC 732-1). A split-plot design was used in which the factorial combinations of fertilizer rate and form of seed tuber were assigned to the main plots while the varieties occupied the sub-plots. The treatments were replicated three times. Varieties Nicola and RC 767-2 had the heaviest and least leaf and stem dry weights, respectively. Nicola, RC 767-2 and WC 732-1 produced more tubers and unmarketable tuber yield than Greta. Greta and RC 767-2 produced larger tubers than Nicola and WC 732-1. The highest NPK rate of 900 kg ha-1 resulted in the heaviest leaf and stem. Optimum tuber number and size was attained at the higher fertilizer rate of 600 kg ha-1. Further increase above 600 kg NPK ha-1 depressed tuber number and tuber weight in 1997/98 and tuber size in 1998/99. The same 600 kg NPK ha-1 recorded the least unmarketable tuber yield. None of the factor measured was affected by type of seed tuber. In conclusion RC 767-2 had the highest plant dry weights as well as more tubers and unmarketable tuber yield that were comparable to that of Nicola and WC 732-1. Greta and RC 767-2 had larger tubers than the other two varieties. The plant dry weights were optimized at 900 kg NPK ha-1 while more tubers of larger size were maximized at 600 kg NPK ha-1. The medium NPK rate of 600 kg ha-1 had least unmarketable tuber yield. Planting of either whole or cut tuber sett did not affect any of the parameter.