Tilmicosin is a macrolide antibiotic used in this study for management of experimentally infected chicken with Mycoplasma gallisepticum (Mg). Its efficacy was assessed by ELISA, re-isolation, lesion score and performance parameters. One hundred and ten day old chicks, tested negative M. gallisepticum, were deployed and equally divided into four groups in separate rooms. On the third week of age, group B was inoculated with 0.2ml of M. gallisepticum broth (10⁸ CFU) into air sac. Group A was likewise infected but treated with tilmicosin phosphate in drinking water at fourth week of age. Group C treated in the same way but not infected while group D was left as control not infected/treated. On weekly basis swabs and serum samples were collected from each group for bacteriology and serology meanwhile morbidity, mortalities and weight gain were recorded. At the end of the experiment results showed that there was no significant differences in mean body gain of groups A, C and D 1606.61±5.79^b, 1658.04±17.01^a, 1624.60±17.36^ab, respectively while there was significant reduction of ELISA antibody titer of group A which recorded 441.22±7.57^bprobablereactors confirmed negative by bacteriological isolation comparingwithgroupB positive Mg at titer 1011.30±40.92^a. It is proved that medication with tilmicosin phosphate in drinking water for 3 successive days was effective in curing of induced M. gallisepticum infection, moreover it was successful to overcome economic problem due to weight loss consequently marketability.