In this paper the need for standardized calibration procedures for automated non-invasive measurement of blood pressure is highlighted. In particular, the IEC 60601-2-30, the EN 1060 and the ANSI/AAMISP-10 are described. A critical overview of the existing standards and protocols dealing with the calibration of these devices is provided focusing on the device specifications and the test methods, including the most used clinical protocols like the British Hypertension Society one. The analysis of the reported references put in evidence the need for a clear and unique set of definitions and objective methods for calibrating blood pressure measuring devices. The IEEE PI 721 project for a new standard on Objective Measurement of Systemic Arterial Blood Pressure in Humans started recently with such purposes.