Interactions between each of the ionophores semduramicin (Aviax), salinomycin (Sacox) with each of ciprofloxacin, erythromycin and suphadimethoxin-trimethoprim were investigated. The ionophore under investigation was fed for 28 days to 48-hours baby chicks prior to 7 days medication with each of the previously cited antimicrobial and/or ionophores at recommended levels. Groups of dirds contained negative non-medicated controls, ionophore alone, antimicrobial alone and ionophore plus other antimicrobial.Different diagnostic criteria were used. Clinical and toxic signs were detected in groups fed semduramicin and medicated with ciprofloxacin and in groups fed salinomycin and treated with erythromycin. However, spasmodic clonic spasms and incoordination disappeared few hours post appearance. Water consumption was significantly dropped in groups fed semduramicin or salinomycin and supplied with sulfonamides and in groups fed salinomycin and supplied with erythromycin. Reductions in body weight were significantly seen in groups fed salinomycin and supplied with sulphonamides. Relative organ weight of spleen and bursa of Fabricious was not altered by any treatment while the relative liver weight was significantly reduced in groups fed semduramicin and supplied with erythromycin. Biochemically, the aspirate transaminase (AST) level was significantly increased in all medicated groups than in non-medicated negative controls. The uric acid was significantly increased in the groups fed salinomycin and medicated with erythromycin or sulphonamides and in groups fed semduramicin and medicated with sulphonamides. Creatinine phosphokinase (CPK) level was significantly increased in groups fed semduramicin or salinomycin and in those medicated with erythromycin or sulphonamides and significantly decreased in group fed semduramicin and treated with sulphonamides.