Amoxicillin, a new, orally administered, semisynthetic penicillin with an antibacterial spectrum similar to that of ampicillin but with increased gastrointestinal absorption, has been shown to be effective against infections produced by a variety of gram-positive and gram-negative bacteria. High rates of cure were achieved in the treatment of pharyngitis due to β-hemolytic Streptococcus and otitis media caused by Haemophilus influenzae, Diplococcus pneumoniae, and Streptococcus pyogenes in both children treated with an oral suspension and adults taking capsules thrice daily. Bronchitis and pneumonia also showed high rates of response in adults. Urinary tract infections produced by susceptible microorganisms, Escherichia coli, Proteus mirabilis, and enterococci, responded to 250 mg given three times a day. Uncomplicated gonococcal urethritis in the male and cervical gonorrhea in the female showed cure rates of >96% when treated with a single 3.0-g dose. Infections of soft tissue, such as streptococcal cellulitis and impetigo, were rapidly cleared by amoxicillin treatment. Cure rates with amoxicillin were usually equivalent to those achieved with twice as much ampicillin. Side effects were uncommon. Rash occurred in few individuals, and gastrointestinal intolerance was rare.