With the technological advancements in information technology, cloud computing provides several opportunities and services to users like storing personal information, accessing various web services for online transactions, online diagnosis systems etc.,. But security in cloud is biggest challenge which poses threat to individual privacy and misuse without knowledge of data owner. In such a situation, secure decision making based on patient information through web services using cryptographic techniques need to be adopted to protect sensitive data for diagnosis. In this paper, the authors propose a novel approach development of cloud model for medical diagnosis expert system in which patient access is divided into two ways.