Abstract: An experiment was conducted to determine optimum sowing time for different varieties of blackgram in Jamalpur region (AEZ-9) of Bangladesh. Pooled analysis exhibited a significant variation among the varieties in respect of seed yield. Barimash-3 produced the highest seed yield (977 kg/ha) which was statistically similar to that of Binamash-1 (960 kg/ha). Barimash-2 produced the lowest seed yield (866 kg/ha). Sowing dates exerted significant effect on seed yield. First sowing (31st August) produced significantly highest seed yield (1168 kg/ha) while the lowest seed yield (541 kg/ha) was found in the latest (28 September) sowing. Interaction also produced significant effect on seed yield. The highest seed yield (1225 kg/ha) was recorded from Barimash-3 with August sowing while the lowest (404 kg/ha) was found in Barimash-2 with Sep. 28 sowing. All varieties produced maximum seed yield with August sowing. Barimash-3 and Binamash-1 performed better than others with delayed sowing up to Sep. 14 during both years.