To study the effect of dates of sowing and improved cultivars on growth and yield of summer sesame in North Bengal five different dates of sowing (10 th February, 20 th February, 2 nd March, 12 th March and 22 nd March and three cultivars of sesame (Rama, Savitri and Tillotama) with three replications. The highest (114.66 and 115.83 cm) plant height was recorded when sesame sown on 12 th March (D 4) and which was statistically at par with 2 nd March (D 3). Among the varying date of sowing, the highest dry matter accumulation, leaf area index and crop growth rate was recorded in 2 nd day of March compared to the other date of sowing. Among the improved cultivars of sesame, the variety Rama recorded higher plant height, dry matter accumulation, leaf area index and crop growth rate compared to Savitri and Tillotoma. The highest yield was recorded when sesame sown on 2 nd March which was 55.99 and 40.85% higher than the crops sown on 22 nd March during 2013 and 2014 respectively. Rama also exhibited highest seed yield recording 17.70 and 12.06% higher than the cultivars Tillotama and Savitri. The date of sowing significantly influenced the yield attributes and highest yield attributes was recorded when sesame sown on 2 nd March. Improved cultivar, Rama recorded the highest yield attributing characters compared to the Savitri and Tillotoma. It can be concluded that sowing of sesame within 2 nd March to 12 th March is the optimum sowing dates of sesame to have optimum seed yield if grown as late summer crop. Result indicated that cultivar Rama can be adopted in terai zone of West Bengal during summer season, because of its highest seed yield ability.