Matlab 5 now supports the use of classes, which can be thought of structures that contain both data and functions (class methods). (In contrast, a struct contains only data.) One class can be derived from another class (the base class), meaning that it inherits the properties--data and methods--of the base class. Also, Matlab now supports overloading of functions. Through these mechanisms, Matlab enables object-oriented design of programs.
For more information, see help class.