A total of 28 samples were collected from the 385.8-386.4 mcd section at ODP Site 1144, northern South China Sea, and microtektites, planktonic foraminifera and stable isotopes were studied in order to evaluate the effects of a mid-Pleistocene impact on microplanktonic communities and the environment. Mid-Pleistocene microtektites were recovered from the interval between a core depth 386.12 and 386.38 mcd, but were concentrated in a 3 cm-thick layer between 386.22 and 386.25 mcd. The average sedimentation rate was 38 cm/ka and the sample's time resolution was 26 a/cm. The results show that the mid-Pleistocene impact appears to have had a minor and short-term (-100 year) effect, causing a -2 degrees C decrease in sea-surface temperature, a corresponding increase in delta (super 18) O and in the abundance of cool-water species, and a decrease in the abundance of warm-water species. However, no planktonic foraminiferal extinction or origination, major shift in sea water stable isotopes, or catastrophic change in environmental conditions were observed.