The stability of the new carbapenem antibiotics, panipenem, meropenem and LJC 10,627, against porcine and human renal dehydropeptidase-I (DHP-I) was compared with that of imipenem. The order of stability to hydrolysis by renal DHP-I was: LJC 10,627 >meropenem >panipenem >imipenerm. After incubation of the drugs with porcine or human enzyme at 30°C for 4 h, the percentages of residual activity were as follows: LJC 10,627, 73·7% and 95·6% respectively; meropenem, 0·2% and 28·7%, respectively; panipenem, 0% and 4·3%, respectively; and imipenem, 0% and 0·1%, respectively. These results demonstrate that LJC 10,627 has extremely high stability against renal DHP-I.