Abstract: The basic features of object-oriented software makes itdifficult to apply traditional testing methods in object-orientedsystems. Control Flow Graph (CFG) is a well-known model used foridentification of independent paths in procedural software. This paperhighlights the problem of constructing CFG in object-oriented systemsand proposes a new model named Extended Control Flow Graph (ECFG) forcode based analysis of Object-Oriented (OO) software. ECFG is a layeredCFG where nodes refer to methods rather than statements. A new metrics--- Extended Cyclomatic Complexity (E-CC) is developed which is analogousto McCabe's Cyclomatic Complexity (CC) and refers to the number ofindependent execution paths within the OO software. The different waysin which CFG's of individual methods are connected in an ECFG arepresented and formulas for E-CC for these different cases are proposed.Finally we have considered an example in Java and based on its ECFG,applied these cases to arrive at the E-CC of the total system as wellas proposed a methodology for calculating the basis set, i.e., the set ofindependent paths for the OO system that will help in creation of testcases for code testing.