A total 110 one-day-old chicks were used in this study to investigate antibacterial effects of organic acid (formic and propionic acid) either alone or together against Salmonella pullorum (Sal. pullorum). 10 chicks were slaughtered and examined bacteriologically to prove that chicks were free from salmonella, the remender100 broiler chicks were divided into 5 groups (20 chicks/each), 1^st group healthy chicks (negative control), At 14^th day of age broilers in group 2^nd, 3^rd, 4^th and 5^th experimentally infected with Sal. pullorum, 2^nd group infected chicks (positive control), 3^rd group chicks received 0.1 ml formic acid /liter drinking water from 1^st to 35^th day of age and infected with Sal. pullorum, 4^th group chicks received 0.1 ml propionic acid/liter drinking water from 1^st to 35^th day of age and infected with Sal. pullorum. 5^th group received formic acid and propionic by same dose, period and route of infection with Sal. pullorum. At 1^st day post supplementation, 5 chicks from each group were slaughtered and two blood samples were taken for estimation of hematobiochemical parameters. Cloacal swabs were collected for salmonella reisolation. Infected broilers showed clinical signs represented by anorexia, closed eyes diarrhea, dehydration, mortality rate 30% and reduction in body weight gain, RBCs, Hb, PCV%, MCHC, lymphocytes total protein, albumin, CAT and SOD beside significant increase in FCR, MCV, MCH, WBCs, heterophil, monocyte globulin, ALT, AST, ALP, uric acid creatinine and MDA, associated with an insignificant decrease in esinophil and basophil. Broilers received formic acid or propionic acid either alone or together for 35 days and infected with Sal. pullorum showed no clinical signs, insignificant decrease in RBCs, Hb, PCV%, MCHC, lymphocyte eosinophil, T. protein, albumin, A/G ratio, CAT, SOD and insignificant increase in weight gain, MCV, MCH,WBCs, heterophil, basophil, monocyte globulin, ALT AST, ALP, uric acid, creatinine and MDA, improved FCR, reduced mortality rate to 5% but both acids together induced zero mortality beside reduction in re-isolation of Sal. pullorum. It could be concluded that, formic and propionic acid play an important role in the control of salmonellosis in broiler and act as growth promoters besides improved hematobiochemical parameters so we recommend using formic acid and propionic acid allover the fatting period.