Abstract: The objective of the current study was to determine the allelopathic potential of six Brassica species widely cultivated in Turkey which are round white radish (Raphanus sativus L.), garden radish (Raphanus sativus L.), black radish (Raphanus sativus L. var. niger), little radish (Raphanus sativus L. var. radicula), turnip (Brassica campestris L. ssp. rapa) and rapeseed (Brassica napus L. ssp. oleifera DC.) cultivar Westar on the germination and seedling growth of cutleaf ground-cherry using shoot powder extracts. Allelopathic effects of shoot powder extracts of six Brassica species at various concentrations (2, 4 and 8%) on cutleaf ground-cherry (Physalis angulata L.) were investigated under laboratory conditions. There were differences among Brassica species for allelopathic inhibition of cutleaf ground-cherry seed germination and seedling growth. Shoot powder extracts of Brassica species exhibited marked differences in the inhibition of cutleaf ground-cherry seed germination. Inhibition on seedling growth was not as much as inhibition on germination. The inhibitory effects of shoot powder extracts on cutleaf ground-cherry seed germination and seedling growth increased as their concentrations increased. These results imply that Brassica species have great potential for cutleaf ground-cherry control. However, more research is needed under field conditions to investigate allelopathic potential and practical applications.