in this study we investigated the influence of acidifiers (Gallimix) on the disposition Kinetics and tissue residues of Lincomycin following single i.v and oral administrations (20 mg/kg b.wt). Lincomycin serum concentration was determined by microbiological assay method. following i.v injection, Lincomycin serum concentration versus time curve was best fitted a 2-comparment open model. It is clear that there is no significant differences in the values of distribution rate constant (α) and distribution half-life (t_1/2a) of Lincomycin following single oral administration of Lincomycin in chickens fed acidifiers containing ration (lppm), the peak concentration (C_max) was 5,63±1.42 mg/ml and was achieved at T_max (0.62±0.23) which is significantly lower (C_max) and shorter T_max than chickens fed on free acidifiers. The calculated bioavailability (F %) was 54.99±7.54% which is significantly lower than the corresponding one (80.13±4.68%) in chickens fed on acidifiers free ration. The average value of protein binding percentage of Lincomycin to chicken's serum proteins was 14.5±1.26%. Following residue studies the obtained results revealed that Lincomycin was found widely distributed in chickens fed acidifiers free ration. In conclusion: concomitant administration of Lincomycin and Gallimix in broiler chickens must be not recommended as the interaction between them significantly reduces Lincomycin blood concentration and tissue distribution which consequently decreases its therapeutic efficacy.