Acceptance of Web- Based marketing information system has remained a topic of interest for the last few decades. Several theories, specifically over the conceptualisation of the technology acceptance model (TAM) have emerged and they have been applied in different contexts to investigate new insights into the acceptance behaviour at individual and organisational levels. The purpose of the research was to determine whether a relationship exists between satisfaction, security, performance and acceptance of internet- based marketing information systems among microfinance institutions (MFIs) in Nairobi Region, Kenya. The study employed simple random and purposive sampling technique for selection of the samples. Anonymous and self-administered questionnaires were distributed to 383 respondents. A total of 370 usable responses were received, resulting in a response rate of 96.6% which was considered satisfactory for subsequent analysis. The findings reflected participants’ high satisfaction and performance level with the usage of Web- Based MKIs but had reservations about the security level of their personal data in the system.