A DISSERTATION SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE IN CROP SCIENCE OF SOKOINE UNIVERSITY OF AGRICULTURE. MOROGORO, TANZANIA.Rice, (Oryza sativa) accounts for more than 50% of the staples consumed in Zanzibar. However, only 20% of the annual demand is produced whereas the remaining 80% being imported. Adoption of improved varieties and better soil management practices may increase rice productivity. An experiment was conducted at Mchangamdogo village, Wete district, during the 2012 rice-growing season to test newly released high fertilizer responsive NERICA varieties and different fertilizers rates that can maximize yield. A Randomised Complete Block Design in a factorial arrangement was used to test the varieties and the fertilizer rates in three replications. NERICA 1, 10 and 12 released by Kizimbani Research Institute and Machuwa local variety were used. Urea (46%N) at 0, 40, 80 and 120 kg N ha-1 and TSP (46%P2O5) at 0, 30 and 50 kg P ha-1 were used as Nitrogen and Phosphorus sources respectively. Growth and yield parameters measured were plant height, panicles per square metre, 50% heading, 80% maturity, biomass, harvest index, panicle length, spikelets per panicle, filled grains per panicle, 1000-grain weight and grain yield. Statistical analysis showed NERICA to be significantly (P≤0.001) superior to Machuwa local variety in all parameters except for plant height. Significant differences were observed among different nitrogen-phosphorus fertility levels. Application of 40 kg N + 30 kg P and 80 kg N + 50 kg P ha-1 was the best for grain yield, 1000-grain weight, panicle length and grains per panicle for NERICA varieties. Interaction effects were highly significant (P≤0.001) at NERICA 12 x 40 kg N + 30 kg P and 80 kg N + 50 kg P ha-1. Therefore, NERICA 12 and 10 can substitute Machuwa local, similarly combination of 40 kg N + 30 kg P ha-1 or 80 kg N + 50 kg P ha-1 was recommended for NERICA varieties in Zanzibar.