The carbapenems are a group of beta-lactam antibiotics, which are similar to the penicillins. In contrast to penicillins, they have a carbon instead of a sulphur atom in the 1-position and an unsaturated bond in the five-membered A ring. There are presently three members of this group that are used clinically, imipenem-cilastatin, meropenem, and ertopenem. Since they are beta-lactam antibiotics they inhibit peptidoglycan synthesis in bacteria by binding to penicillin-binding proteins. All carbapenems are lipid-insoluble compounds that are not absorbed from the gastrointestinal tract after oral administration. Their pharmacokinetics, especially imipenem, is complicated by renal metabolism, necessitating combination with cilastatin. This is not required for the others in this group. The carbapenems have a uniquely broad antibacterial spectrum covering a majority of gram-negative and gram-positive, aerobic and anaerobic cocci and bacilli. They are characterized by stability to beta-lactamase-mediated resistance. Carbapenems are indicated mainly as empiric monotherapy in serious infections, such as intra-abdominal infections and infections in neutropenic patients. They are also useful in the treatment of mixed bacterial infections and aerobic gram-negative bacterial infections that are not susceptible to other beta-lactam antibiotics. The carbapenems are generally well tolerated drugs. The most common clinical adverse events seen with these agents are local injection site effects, gastrointestinal disturbances, and dermatological reactions. Seizures are the most serious side effect, especially with imipenem.