The wireless network technology with its gradual advancements is adapted by many domains like banking, governance, health services, etc., where most of their transactions include customer’s sensitive data. Along with advancement in the network technologies, digital crime is also increased at high rate. This may cause loss of sensitive data through malicious activities in the network. This concern of network security system can be effectively handled through the strong authentication mechanism. It can be observed that multiple authentication mechanisms that are currently used in the wireless digital network are vulnerable towards various advanced malicious techniques. Hence, there is a need to strengthen the existing authentication mechanisms or to design a stronger authentication mechanism. This paper considers the vulnerabilities identified in a two-factor authentication scheme for online medical services proposed by Li et al. and further proposes an enhanced two-factor authentication that overcomes the vulnerabilities analysed from Li et al. mechanism. Copyright © 2020 Inderscience Enterprises Ltd.