Weeds growth in crops causes more economic losses to crops than any other pest. The conventional control methods have given rise to serious issues of environment and human health. The importance of development of alternative techniques based on biological approaches has increased. In the present study, allelopathic bacteria were evaluated for suppression of weeds associated with wheat. A large collection of rhizobacteria was obtained from the rhizosphere of wheat and its associated weeds (wild oat, little seed canary grass, broad leaved dock, common lambs’ quarter and field bindweed) which were in turn sampled from chronically infested wheat fields. These rhizobacterial strains were screened through in vitro bioassays based on production of phytotoxic metabolites i.e., HCN production, E. coli antimetabolite assay and lettuce seedling bioassay. Eighty nine of 393 rhizobacterial strains were found to be cyanogenic. Nineteen of the 89 cyanogenic strains inhibited the growth of sensitive E. coli strain K12 due to antibiosis. These 19 strains were applied to lettuce in agar bioassay on Petri plates. Growth of lettuce seedlings was inhibited by 6 strains, 5 significantly increased while 8 strains did not affect the growth of lettuce seedlings. These 19 strains were applied to wheat and 4 weeds (wild oat, little seed canary grass, broad leaved dock and common lambs’ quarter) in similar agar bioassay. Results indicated non-selective inhibition of all the weeds and wheat due to inoculation with 2 strains. Three strains selectively inhibited the germination and growth of weeds but also suppressed wheat. Three strains selectively inhibited weeds and remained non-inhibitory to wheat. However, 9 strains selectively inhibited weeds and promoted the growth of wheat. Ten strains from the later 2 groups were re-tested on 3 weeds and wheat under axenic conditions in growth room. Twenty five days old plants were measured for different growth parameters. The applied strains caused inhibition of germination and dry matter of wild oat from 15.2 to 63.3 and 12.4 to 65%, little seed canary grass from 18.5 to 58.7 and 22.8 to 81.4% and broad leaved dock from 18.4 to 60.5 and 21.7 to 71.3% than their controls, respectively. Four of these strains improved the growth of wheat while others remained non-inhibitory. Five strains from the previous study (T42, L9, 7O₀, O₀10 and W9) were selected to study effects of allelopathic bacteria on 3 weeds (wild oat, little seed canary grass and broad leaved dock) grown in wheat and infested wheat in pot and field trials. Infestation of wild oat caused reduction in grain yield of wheat up to 60.8% than weed free control. Suppression of wild oat by strain T42, L9, 7O₀, O₀10 and W9 controlled the loss in grain yield of infested wheat up to 60.0, 73.6, 35.8, 22.0 and 49.7%, respectively. Infestation of little seed canary grass caused loss in grain yield of infested wheat up to 59.9% than weed free control. Suppression of this weed by strain T42, L9, 7O₀ and O₀10 recovered the loss in grain yield of infested wheat up to 20.1, 55.0, 66.9 and 59.0%, respectively. Infestation of broad leaved dock caused loss in grain yield of infested wheat up to 55.8% than weed free control. Suppression of this weed by strain T42, L9, 7O₀ and W9 controlled the loss in grain yield of infested wheat up to 45.2, 53.9, 46.3 and 68.0%, respectively. These effects of allelopathic bacteria were also evident from other growth, yield and physiological parameters of weeds and infested wheat. Infestation of weeds caused loss in grain yield of infested wheat up to 54.1, 53.9 and 56.3% than weed free control, respectively. In field trial I, suppression of broad leaved dock and common lambs’ quarter controlled the loss of grain yield of infested wheat up to 38.3, 64.0, 51.0 and 62.9% due to inoculation with strain T42, L9, 7O₀ and W9, respectively. Suppression of little seed canary grass in field trial II controlled the loss in grain yield of infested wheat up to 34.3, 55.1, 64.3 and 57.2% due to inoculation with strain T42, L9, 7O₀ and O₀10, respectively. In field trial III, suppression of wild oat and little seed canary grass controlled the loss in grain yield of infested wheat up to 47.9, 60.7, 53.7, 29.0 and 36.6% due to inoculation with strain T42, L9, 7O₀, O₀10 and W9, respectively. These effects of allelopathic bacteria were also evident from other growth, yield and physiological parameters of weeds and infested wheat. Under weed free conditions, these strains remained noninhibitory to wheat. Instead, inoculation with strain L9 and 7O₀ significantly improved the growth and yield of wheat. Microbiological and biochemical characterization of these strains also revealed the possession of molecular characteristics of weed suppression and plant growth promotion, and identified as Pseudomonads. This research suggests utilization of allelopathic bacteria to control weed infestations in wheat and avoid harmful effects of other weed control techniques on human health and environment.