A high-performance liquid chromatography method for the determination of ertapenem in human plasma using ultraviolet detection (300 nm) was developed and validated. The method involved a simple organic protein precipitation that guarantees rapid sample preparation. By using meropenem as internal standard, it also guarantees improved precision (relative standard deviation <3.70) and accuracy (deviation from true value <6.58%). The method was linear from 0.59 to 150 microg/mL and reproducible. In conclusion, this method allows the measurement of ertapenem in human plasma and may be used for both clinical routine applications and pharmacokinetic studies.