Abstract: The method of determining systolic and diastolic blood pressure where the set of received data of each curve of the plethysmographic curve gained from the unit for monitoring the life functions in a shape of the ring and/or the earring is divided into individual segments that respond to one heartbeat of the measured subject and after processing there are selected and recalculated segments meeting the defined criteria. The unit for monitoring and measuring the life functions comprises a supporting construction in a shape of a ring (29) and/or an earring (39).