The study was carried out to document the density, survival and seed production potential as seed rain, through a single value, of important weeds under different cropping systems at the districts Bankura, Birbhum and Burdwan representing lateritic belt of West Bengal during 2011-12 and 2012-13. Twenty four weed species under 22 genera and 14 families were studied in 9 crops. Highest density was recorded in Mollugo stricta in rice under rice – rice system, in Oldenlandia corymbosa in rice under rice – wheat/mustard/ vegetables system, whereas Digitaria sanguinalis recorded highest density in winter and pre-Kharif crops. Highest survival per cent was recorded in Commelina nudiflora and seed rain in Spergula arvensis.