In order to study the effects of different irrigation intervals and plant density on morphological characteristics, grain and oil yields of sesame, an experiment was conducted at experimental station, college of agriculture, Ferdowsi University of Mashhad. Four different irrigation intervals (one, two, three and four weeks) with four plant densities (20, 30, 40 and 50 plants/m2) were compared in a spilt plot arrangement based on randomized complete block design with four replications. Irrigation intervals and plant densities allocated in main plots and subplots, respectively. Different characteristics such as plant height, distance of first capsule from soil surface, number of branches per plant, number of grains per capsule, number of capsules per plant, grain yield, 1000-seed weight, harvest index and oil yield were recorded. The results showed that there were no significant difference between different irrigation intervals in terms of distance of first capsule from soil surface, number of grains per capsule, 1000-seed weight and harvest index. Different irrigation intervals had significant effects on plant height, number of branches per plant, number of capsules per plant, grain yield and oil yield. There were significant differences between different plant densities in terms of distance of first capsule from soil surface, number of branches per plant, number of graines per capsule, number of capsules per plant, grain yield, harvest index and oil yield. The highest grain yield (798/7 kg/ha) and oil yield (412/8 kg/ha) were obtained at one week and four weeks irrigation intervals, respectively. Between all treatments, 50 plants/m2 and one week irrigation interval produced the highest grain yield (914/7 kg/ha) and oil yield (478/6 kg/ha). Because of shortage of water in Mashhad condition, the results recommended that, 50 plants/m2 and two weeks irrigation interval produced rather acceptable grain yield, with less water consumption.