During the last 10 years, a continuous increase in the incidence of beta-lactamase-producing Haemophilus influenzae has been observed; in addition, beta-lactamase-negative ampicillin-resistant strains are better identified and more frequently isolated. During the same period, resistance to tetracyclines and chloramphenicol decreased to a very low level. The incidence of resistant bacteria is highly variable according to the site of infection, patient's age, type of Haemophilus, and country or region, according to local epidemiological factors. Follow-up multicenter studies are needed to monitor the evolution of resistance to these antibiotics and also emergence and spread of resistance to other antibiotics, such as new fluoroquinolones, new beta-lactams, and new macrolides.