The Authors shortly present some statistical and epidemiological data on RTI and stress that these infections are nowadays the main infectious diseases. After an excursus of the most frequent infectious aetiologies, they show their experience in RTI treatment, mainly acute LRTI, with a new fluorquinolone, ciprofloxacin, at the posology of 250 mg p.o. b.i.d. or t.i.d., with good clinical results (90% of recovery) and excellent tolerability (absence of ADR in 100% of the treated patients).