Two field experiments were conducted during 2008 and 2009 cropping seasons at the Educational Farm, Faculty of Agriculture, Sana'a University. Phenological and productivity characteristics of two sesame (Sesamum indicum L.) cultivars under different nitrogen rates were investigated. The experiments were laid out in a split plot design with N levels of 0, 50, 100 and 150 kg N/ ha^-1 assigned to the main plots and the two sesame cultivars (Kod-94 and Local) assigned to the subplots. The interaction effects between used nitrogen levels and cultivars were tested. Plants growth and development behavior was studied during the different periods from seedling to harvest time. Data indicated that increasing nitrogen rates by 0, 50 and 100 up to 150 kg N per hectare significantly increased growth of plant traits, yield/ha and yield components. Both tested cultivars of sesame differed significantly in number of leaves per plant, 1000 seed weight, length of capsule and oil percentage. Sesame cultivar Kod-94 was superior in yield/ha and yield components over sesame cultivar Local. Growth characters, yield/ha and yield components significantly enhanced the positive interaction between N fertilizer levels and sesame cultivars. The maximum value (1.26) seeds yield ton/ha and oil percentage (51.7%) were obtained when sesame cv. Kod-94 was fertilized by 150 kg N/ha. While, the lowest values of these two characters were recorded in plots with zero nitrogen whatever the sesame cultivar grown was. Data showed clearly that the local cultivar was very susceptible to powdery mildew, while sesame cv. Kod-94 was very resistant as no symptoms of the disease was recorded at all growth stages and with all nitrogen fertilizer treatments.