Undesirable growth of potato (Solanum tuberosum L.) crop under an excessive N fertilizer application is a potentially serious problem. This research was conducted to investigate the response of different potato cultivars; Russet Burbank, Shepody, and Superior, and its qualitative characteristics under a series of N rates. Six rates of N fertilization (0–280 kg ha-1) were applied on 11 sites in a randomized complete block design, with four replications. Sites with =30 g kg-1 of soil organic matter (OM) produced total tuber yield, marketable yield, and tuber weight per plant 39.5, 45.2, and 54.9%, respectively, higher than sites with =30 g kg-1 of OM. Tubers specific gravity increased by 0.18% in the sites with =30 g kg-1 of OM. The total tuber yield for the three cultivars was maximized at 168 kg N ha-1. Marketable specific gravity, starch, and dry matter content were achieved by applying 168 and 112 kg N ha-1 at =30 and =30 g kg-1 of OM sites, respectively. Russet Burbank produced a higher yield than Shepody and Superior cultivars significantly, but there was no significant difference among them regarding specific gravity. Excessive N application (>168 kg ha-1) decreased potato tuber production and quality. [Full Text]