AbstractRealtime telemonitoring of critical, acute and chronic patients has become increasingly popular with the emergence of portable acquisition devices and IP enabled mobile phones. During telemonitoring, enormous physiological signals are transmitted through the public communication network in realtime. However, these physiological signals can be intercepted with minimal effort, since existing telemonitoring practise ignores the privacy and security requirements. In this paper, to achieve end‐to‐end security, we first proposed an encoding method capable of securing Electrocardiogram (ECG) data transmission from an acquisition device to a mobile phone, and then from a mobile phone to a centralised medical server by concealing cardiovascular details as well as features in ECG data required to identify an individual. The encoding method not only conceals cardiovascular condition, but also reduces the enormous file size of the ECG with a compression ratio of up to 3.84, thus making it suitable in energy constrained small acquisition devices. As ECG data transfer faces even greater security vulnerabilities while traversing through the public Internet, we further designed and implemented 3 phase encoding—compression—encryption mechanism on mobile phones using the proposed encoding method and existing compression and encryption tools. This new mechanism elevates the security strength of the system even further. Apart from higher security, we also achieved higher compression ratio of up to 20.06, which will enable faster transmission and make the system suitable for realtime telemonitoring. Copyright © 2008 John Wiley & Sons, Ltd.