Omer HHM, Mohammed IS. 2018. Allelopathic effects mesquite (Prosopis juliflora) aqueous extracts on seeds germination and seedling growth of alfalfa, sesame and sorghum. Cell Biol Dev 2: 51-54. Mesquite plant [Prosopis juliflora (Swartz) DC] is an invasive tree or shrub, native to South America. Unfortunately, due to deliberate distribution within Sudan, the plant poses a threat to biodiversity and agriculture. This plant has allopathic potential that may be caused by falling leaves, fruits, roots exudates or plant leachates. These allelochemicals may inhibit the germination and growth of agricultural crops. This study was conducted in the Laboratory of Plant Pathology, College of Agricultural Studies, Sudan University of Science and Technology, karthoum on January-February 2016. The aim of this study was to elucidate the potential of allopathic effects of aqueous extract of different parts of mesquite plant, i.e., leaves, fruits, bark, and roots, on germination and early seedlings growth of alfalfa, sesame, and sorghum. The results indicated that the aqueous extracts of different parts of mesquite plant significantly ( P ≤ 0. 05) inhibited the seeds germination and reduced the early growth of the seedlings. These suggest that the inhibitory substance (s) were widely distributed in mesquite plant but at varying extents. Moreover, fruits and leaves extracts was more pronounced and consistent than bark and roots. This could be attributed that the mesquite fruits and leaves aqueous extracts contain or water-soluble allelochemicals than that of roots and bark. They gave 0.0% germination in alfalfa and sesame and 47.6-86.7% in sorghum, respectively, compared to control. Whereas the length of hypocotyl and radical was reduced to 0.0 cm and up to 2.7 cm depending on the efficacy of extract and the response of the test crop. Thus, it is recommended to study the nature of inhibitor sto determine whether allelopathic is the cause of the extraordinary success of mesquite on the flat plains of agricultural land in Sudan.