Background. Lysophosphatidic acid (LPA) receptor 3 expressed in the uterus plays a critical role in uterine receptivity for the embryo. We investigated whether human embryos produce LPA by analysis of a human embryo-conditioned medium (HECM). Methods. LPAs in HECM were extracted by the Bligh-Dyer method. Extracted LPAs were converted to trimethylsilyl (TMS) derivatives. Gas chromatography (GC)/ selected ion monitoring (SIM) and GC / mass spectrometry (MS) were used to analyze LPAs derivatized with TMS. Monitoring and quantitative analysis of LPAs were performed using GC/SIM with [M-15] ion derived from LPAs. Identification of LPAs was confirmed by GC/MS. Results. LPA-C16:0, 16:1, 18:0, 18:1 and 18:2 were detected in HECM. The concentration of LPAs was calculated by comparing each detected peak area with a corresponding standard LPA. Conclusion. This study is the first study in which five molecular species of LPAs produced by human embryos were detected in HECM and their quantities analyzed.