The study presents the major factors for Internet banking adoption and compares the levels of adoption across countries, in order to identify more easily what factors to consider most while providing banking services over the Internet. Based on prior studies, web security, Internet usage, economy status, high branch intensity, competition, government prioritization regulations, and literacy level were identified as the major factors affecting Internet banking adoption. This study uses fuzzy inference systems (FIS) to define the adoption rate. Our experimental results show that security is the most important factor because no matter how high government prioritization, literacy level, Internet users, and competition among Internet service providers are, as long as there are low security levels, the adoption rate will be at the lowest level. We conclude that, overall, the banks-specific factors are the main drivers for Internet banking adoption.