Theimmunomodulatory effectsofantibioticscouldinfluencethedegreeofsystemicandlocalresponsestoinfection,soinvestigationoftheirintrinsicinfluenceonthehost’sinflammatoryresponseappearstobeessential.Fluoroquinolonesareknowntoexertmodulatoryactivityonimmuneresponsestomicrobialinfection.Howeverthemechanismofthisimmunmodulationhasnotbeenwellelucidated.Theaimofthework,istoassesstheimmunomodulatoryeffectsofalevofloxacin,throughexaminingitseffectontheconcentrationsoftumornecrosisfactorα(TNF-α)andInterleukin–10(IL-10)inserumofpneumonicpatients.Afterfollowinglocalresearchethicscommitteeapprovalandinformedconsent.Thisstudyincluded 40patientswithdifferenttypesofpneumonia,admittedtodepartmentofChestDiseases,FacultyofMedicine,AssiutUniversityHospitals,Egypt.Also,10healthyvolunteersservedasrandomizedcontrols.Bothpatientsandcontrolsreceivedlevofloxacin(750mgoncedailyfor10days).SerumlevelsofTNF-αandIL-10weremeasuredinpatientsandcontrolbeforeandafterlevofloxacinadministration(750mgoncedailyfor10days)usinghumanTNF–αandIL-10ELISAkitsrespectively.LevofloxacincausedastatisticallysignificantdecreaseinthemeanlevelofTNF-αinbothpatients(20.82±1.31pg/ml)(P0.009)andcontrolgroup(17.12±0.84pg/ml)(P0.004).Incontrast,therewasstatisticallysignificantincrease(P0.000)inthemeanlevelofIL-10inpatients (61.75±2.85pg/ml)whilestatisticallysignificantdecrease(P0.005)incontrolgroup(28.57±1.37pg/ml).Inconclusion,ourstudydemonstratesthattreatmentwithlevofloxacinaffectsproductionofTNF-αasapro-inflammatorycytokineandIL-10asananti-inflammatorycytokineswhichmayprovide additionalbenefitsintreatmentof respiratorytract infectionsthatare independentofitsantibacterialproperties.