Embodiments of the present invention provide a method, system and computer program product for extensible definition of interactive system productivity facility (ISPF) panels. In an embodiment of the invention, a method for extensibly defining ISPF panels can include loading a panel defined by different panel definition statements recognizable by an ISPF facility, and identifying a panel input exit facility amongst the panel definition statements defining the panel. Of note, the panel input exit facility references an external exit module. The method also can include determining an external exit module referenced by the panel input exit facility. Finally, the method includes passing records of the panel to the external input exit facility for pre-processing of the panel outside of the ISPF facility.