In order to determine the best planting date for rapeseed cultivars in paddy fields of Guilan area, this research was carried out at Kouchesfahan, one of the Rasht city dependencies during 1999-2000 growing season. The experiment was conducted as a split plot in randomized complete block design with four replicates. The main plots consisted of four planting dates: October 2 and 17 and November 6 and 21 and the subplots were four rapeseed cultivars:Maluka, Jeriss, Eureka and PF7045/91.The of results variance showed that the effect of between planting dates and cultivars for all traits including grain yield, biological yield, harvest index, plant height, height of the lowest pod bearing branch, 1000-seed weight , number of pods per plant, oil percent, oil yield, germination date, flowering a pod initiation as well as the duration of growing were significantly different. Planting date × cultivar interaction was significant only for oil percent, flowering and pod initiation. The results indicated that the planting date (17 October) was significantly better than the others. Delayed sowing decreased grain yield and negatively affected other agronomical characters significantly. Among cultivars, PF7045/91 produced the highest oil percent and Jeriss ranked the first in other characters.
)