Efforts were made to assess the allelopathic effect of different concentrations (1, 3 and 5%) of leaf extracts of J. curcas on germination and seedling growth of wheat, mustard, til and black gram under bioassay conditions. Three accessions of J.curcas (NRCJ-7, NRCJ-18 and NRCJ-89) were selected for this phytotoxic experiment. The inhibitory effects of the J.curcas extracts on all the test crops were found. The toxicity of the Jatropha accessions was in the order (irrespective of concentrations) NRCJ-18 > NRCJ-7 > NRCJ-89 for wheat; NRCJ-89 > NRCJ-18 > NRCJ-7 for mustard; NRCJ-7 > NRCJ-89 > NRCJ-18 for til; NRCJ-7 > NRCJ-18 > NRCJ-89 for blackgram. From the holistic point of view wheat and til are least affected by Jatropha curcas than mustard and blackgram.