Potato (Solanum tuberosum L.) is one of the most important root and tuber crops in Ethiopia in general and in Amhara Region in particular. Its production and productivity become constrained by poor agronomic practices and lack of high quality and quantity of seed tubers. The present study was carried out in Guagussa Shikudad District of Awi administrative Zone, Northwestern Ethiopia, to determine the effects of intra-row spacing and rate of nitrogen on seed tuber yield of potato under irrigation in 2019. The experiment was laid out in randomized complete block design with four levels of nitrogen (0 , 40.4, 80.8 and 121.2 kg ha-1 ) and three levels of intra-row spacing (20, 30 and 40 cm) in three replications. Growth and yield related parameters were collected and analyzed using SAS 9.2 software. Results revealed that both the main and interaction effects of nitrogen and intra-row spacing significantly (P<0.05) influenced most of the tested parameters including (day to flowering, day to maturity, plant height, tuber yield). On the other hand days to 50% emergence and main stem number were not influenced. Generally increasing nitrogen fertilizer increased Average tuber yield, marketable and seed tuber while widening the intra row spacing increased tuber number per plant and decreased plant density. Combination of 80 kg ha-1 nitrogen with 20 cm intra row spacing recorded the highest seed tuber yield 20.00 t ha-1 , marketable 27.10 t ha-1 and total tuber yields 33.75 t ha-1 . The same treatment combination also recorded the highest net benefit and marginal rate of return, which can be recommended for economical production of seed potato in the study area and areas with similar agro ecology. Repetition of the study in different sites of the study area with different ag