We report here the antibacterial activity of the new penem antibiotic Men 10700 against a total of 740 gram-positive and gram-negative clinical isolates, in comparison to imipenem, meropenem, cefotaxime, ceftriaxone, ciprofloxacin and gentamicin. Men 10700 has shown a wide spectrum of antibacterial activity, with a potent activity both against gram-positive species (with the exception of methicillin-resistant Staphylococcus aureus and Staphylococcus epidermidis) as indicated by minimal inhibitory concentration (MIC₉₀) values ≤0.5 mg/l, and gram-negative species, with MIC₉₀ values generally ≤2 mg/l. Men 10700 was the most potent antibiotic against methicillin-susceptible S. aureus and S. epidermidis, while the overall spectrum of activity resembled that of imipenem; meropenem was more active against most gram-negative species. In comparison with third-generation cephalosporins, Men 10700 demonstrated superior activity against methicillin-susceptible S. aureus and S. epidermidis and some gram-negative species such as Morganella morganii, Serratia spp. and Enterobacter cloacae; moreover, in contrast to third-generation cephalosporins, Men 10700 showed moderate activity against Enterococcus spp. The activity of Men 10700 against penicillin-resistant Streptococcus pneumoniae (10 strains) and some gram-negative strains selected for their resistance to cefotaxime (20 strains) was particularly interesting.