In this study we explored the possible role of arachidonoylethanolamine (AEA) in regulating blood pressure in patients on continuous ambulatory peritoneal dialysis (CAPD). One hundred and five patients on CAPD were enrolled. Volume status was evaluated by the overhydration (OH) value obtained by bioimpedance analysis. OH<2.0 kg was defined as normal volume (NV) and OH≥2.0 kg as high volume (HV). Home mean systolic blood pressure<130 mmHg was defined as controlled hypertension (CHT) and ≥130 mmHg as uncontrolled hypertension (UHT). The patients were divided into four subgroups: (1) controlled hypertension with normal volume (CHT-NV), (2) controlled hypertension with high volume (CHT-HV), (3) uncontrolled hypertension with normal volume (UHT-NV), and (4) uncontrolled hypertension with high volume (UHT-HV). AEA was measured by ultra performance liquid chromatography-tandem mass spectrometry. AEA was significantly higher in the HV group as compared with the NV group (P<0.05). In addition, AEA was also significantly higher in the CHT-HV group as compared with the UHT-NV group (P<0.05). These results may suggest a compensatory function of AEA and TRPV1 pathway to lower blood pressure during volume expansion in CAPD patients.