Wireless body area networks (WBANs) increase the demand of healthcare service to improve the quality of patient’s life. In WBANs, the security issues arise during monitoring of the patient body function and recording. There is a need for effective remote health monitoring service model for enhancing the security and privacy of patient’s medical report. In order to overcome such existing limitations, a secure patient activity data monitoring through privacy preservation technique in handling medical healthcare services of patient in remote locations is proposed. The privacy preservation technique introduced in this work is flexible Naor and Reingold key-based data encryption/decryption (FNRK-DED) model. The FNRK-DED model is applied in conducting the simulation works on parameters such as data privacy rate, security ratio based on patient’s health information, energy consumption rate and response time and is found to be effective. Copyright © 2019 Inderscience Enterprises Ltd.