Field experiments were conducted at the Fadama Farm of Usmanu Danfodiyo University, Sokoto for three consecutive years during 1990-92 rainy seasons. The objective of the investigation was to study the effects of nitrogen, phosphorus and seed rates on two upland rice cultivars with a view to arriving at an optimum combination rates of these factors for optimum paddy yield. The analyzed data revealed that the cultivar Ex-China was significantly superior to ITA 257 in both total and ear-bearing tiller number/unit area, but almost at par with each other in panicle length. ITA 257 was, however, found to be significantly taller and therefore more susceptible to lodging than Ex-China, especially at high nitrogen rates. The latter was found to be of longer duration than the former. In terms of grain number/ear and seed weight, ITA 257 was superior. Also, in view of ITA's tall stature, it tended to produce more straw than its counterpart, in spite of Ex-China's higher tillering ability. Ex-China turned out to be higher paddy yielding than ITA 257. The results also indicated that nitrogen significantly affected most of the growth parameters and paddy yield components, notably tillering, panicle length and plant height. But, in general, the nutrient had no significant effect on time to flowering and maturity. The nutrient aggravated lodging, especially in the relatively taller cultivar, ITA 257. Nitrogen also promoted grain number/ear significantly in most years, but, on the whole, it showed no significant effect on seed weight. It also affected both the straw and paddy yields significantly, but increasing the rates had v i i an adverse effect on grain:straw ratio. Seed rate, either alone, or in interaction with nitrogen or phosphorus also increased most of the parameters examined, but mainly up to 75 kg seed/ha beyond which competition set in. However, lodging and 1000- seed weight were not significantly affected by increasing seed rates. Grain:straw ratio was also little affected by this factor. Phosphorus showed no significant effects on tillering, time to flowering and maturity, straw weight, and grain:straw ratio. However, increasing levels of this nutrient significantly increased panicle length in two out of the three seasons, and in respect of lodging, there was a lower incidence of it with increasing phosphorus rate in only one season. An increase in the phosphorus levels also increased paddy yield in only one season. Polynomial responses to nitrogen and seed rates were, in general, linear, indicating that paddy yield would continue to increase beyond the ranges of the factors tried in this experiment. With regards to phosphorus, however, the response was either inconclusive, or quadratic. Correlation studies revealed that number of ear-bearing tillers/unit area was the single most important paddy yield contributing component, in view of its significant positive correlation with the yield throughout the conduct of the trials. Thus, the other two paddy yield components, i.e., number of grains/ear and seed weight were adjunct to it.