Cefuroxime (CXM) is a new injectable cephalosporin stable against beta-lactamases. The results of preclinical and clinical studies so far carried out in Japan on cefuroxime are summarized in this paper. 1. CXM is stable to various kinds of beta-lactamases except the one produced by P. vulgaris GN 76 (RICHMOND type Ic). Reflecting this action, CXM has been shown to have antibacterial activity, not only against organisms which respond to conventional cephalosporins, but also against Citrobacter, Enterobacter, Hafnia, and Indole positive Proteus which are resistant to conventional cephalosporins. 2. After an intravenous or an intramuscular injection, satisfactory blood levels of CXM are attained with the half-life about 1 hour, and CXM is excreted into urine via kidney in an active form. Transfer of CXM to tissues or various body fluids such as bile, cerebrospinal fluid, prostatic fluid, etc., is also satisfactory. 3. Of the total 826 evaluable cases treated in the open clinical study, 243 cases (29%) were assessed as 'excellent' and 404 (49%), as 'good,' and the efficacy ratio ('excellent' and 'good') was as high as 78%. 4. In a double-blind comparative study vs. cefazolin in patients with respiratory or urinary tract infections, CXM was proven to be superior to CEZ in either the infection, both in terms of clinical efficacy and global utility. 5. Incidence of side effect was very low. Of the total 1,057 cases treated in the open and double-blind clinical studies, side effects, mostly skin hypersensitivity and pyrexia, were noted only in 26 cases (2.5%).