The services offered to the Internet community have been constantly increasing the last few years. This is mainly due to the fact that mobile code has matured enough in order to provide the Internet users with high quality applications that can be executed remotely. When a user downloads and executes code from various Internet sources, security issues arise. In this paper, we are addressing the latter and we present a comparative evaluation of the methods used by Java, Safe-Tcl and ActiveX in order to confront with these issues, based on current security functions and implementations as well as on future adjustments and extensions.