Preliminary in vitro studies of ceftibuten in the United States and Canada have demonstrated a potent activity against enteric bacilli (greater than 90% of routine clinical isolates), Haemophilus influenzae, Moraxella catarrhalis, Neisseria spp., most B-hemolytic streptocci, and Streptococcus pneumoniae. Ceftibuten was demonstrated to be bactericidal, minimally influenced by high inocula, beta-lactamase stable, an inhibitor of type Ia beta-lactamase, and potentially usable against some Enterobacteriaceae strains capable of destroying other newer cephalosporins (ceftazidime and cefixime). In vitro test methods have been standardized, and preliminary quality control guidelines have been proposed for clinical trials. The ceftibuten spectrum seems best suited for therapy of urinary tract, respiratory, and genital tract infections as an alternative to older oral cephalosporins, recently marketed esters (cefuroxime axetil), and cefixime.