Sphingosine-1-phosphate(SPP) is an important second messenger involved in cell growth and cell death. HEK293 cells transcripted with EDG-1, a SPP receptor, were cultured and harvested, and incubated with ³²P labeled or non-labeled SPP. The SPP level was determined based on competitive binding of SPP or ³²P-SPP to HEK cells. This method does not require special apparatus, and able to measure the content of SPP as low as pmol with high sensitivity and good repetition. The between groups deviation was less than 15%.