A field experiment was conducted on alluvial soil at Dakahlia Governorate, Egypt during the growing season of 2007/2008 to study the effect of organic-N as rice straw compost (three levels 0, 6 and 12 t fed^-1), inorganic-N as ammonium nitrate (three rates 60, 120 and 180 kg N fed^-1) and their interaction on potato (Solanum tuberosum, L) cultivar Spunta. Organic-N and mineral-N application significantly increased leaves No./plant, plant height and leaf area. While, the interaction effect between organic and mineral N was insignificantly on leaves No./plant and plant height and  significantly on leaf area. Fresh tuber yield and dry shoot yield significantly increased with compost and mineral-N application and their interaction. The highest value of fresh tuber yield was 19, 28 t fed^-1 with interaction of 180 kg N + 12 t fed^-1 compost. Dry matter % in tubers was significantly affected by mineral-N, compost application and their interaction after 70, 90 and 110 days from planting. Protein percent and specific gravity were significantly affected with mineral-N fertilization, but insignificantly affected by compost application. N, P and K % in shoots and tubers dry matter were increased with mineral nitrogen and compost addition and their interaction as compared with control at different periods.