Urea is the primary N source used in delayed flood rice. Urea has an undesirable characteristic in that it is prone to ammonia volatilization losses if not soil incorporated within a couple of days after surface application. Therefore, the objectives of this study were to determine the influence of ammonium sulfate, Agrotain, and urea on ammonia volatilization losses and grain yield of drill-seeded, delayed flood rice. The study was conducted in 2002 and 2003 with treatments arranged in a randomized complete block design, with a factorial arrangement of 3 N sources x 3 N rates x 3 application times and four replications. Fertilizer N rates were 0, 67, and 134 kg N/ha. The application times for the preflood N fertilizer were 10, 5, and 1day prior to flooding. Over 20 and 15% of the urea N, only 5 and 3% of the ammonium sulfate N, and only 3 and 2% of the Agrotain-N were lost via ammonia volatilization within 5 days of application in 2002 and 2003, respectively. By 10 days after application and the time of flooding, ammonia volatilization ceased from all of the N sources. Application of Agrotain and ammonium sulfate produced the highest grain yields, which were quite similar and were significantly higher than those produced with urea when the flood was delayed for 5 and 10 days in both years. Urea displayed a significant grain yield decline as the time between N fertilizer application and flooding was increased to 5 and 10 days in both years.