The objective of this study was to determine the accuracy of the Microlife BP W100 device for blood pressure measurement. The device evaluations were performed in 85 participants, by using both the protocol of the European Society of Hypertension (ESH) and the protocol of the British Hypertension Society (BHS). Initially, the data from 33 participants were examined according to the ESH protocol. Furthermore, 52 participants were then enrolled to fulfill the BHS protocol requirements. In all participants, sequential same arm measurements were made by two trained observers. The device passed all three phases of the ESH protocol for systolic blood pressure (SBP) and diastolic blood pressure (DBP) and was graded A according to the criteria of the BHS protocol for both SBP and DBP. The A/A grade was achieved in low (<130/80 mmHg), medium (130-160/80-100 mmHg) and high (>160/100 mmHg) blood pressure categories. Mean blood pressure difference between BP W100 and observers in the 85 participants was 0.1+/-5.3 mmHg for SBP and 1.1+/-3.4 mmHg for DBP, and thus, the device also met the requirements of the Association for the Advancement of Medical Instrumentation. In conclusion, these data show that the Microlife BP W100 wrist monitor satisfied the recommended ESH accuracy levels and achieved A/A grade of the BHS protocol across a wide range of blood pressure.