The value of the critical temperature Te and isotope coefficient 0: could be greatlyrnaffected by a number of factors. Among them are the presence of magnetic impurities,rnnon-magnetic impurities, disorder and defects. Following previous calculationrnof the critical temperature and isotope eflect by Singh and Kishore (P. Singh and R.rnKishore, J. Supercond. 8, 9 (1995)), Singh et al. (S. P. Singh, R. K. Pandey, and P.rnSingh, J. Supercond. 9, 277 (1996)), Openov (Phys. Rev. B 58, 9468 (1998)) andrnOpenov et al. (Phys. Rev. B 64,12513 (2001)) we have considered the effect of disorderrn(defect) on the superconducting transition temperature Te and isotope coefficientrn0: with in the BCS model. An expression for Te and 0: as a function of potential andrnspin-flip scattering rates is derived by means of Green's functions technique. This isrndone with the introduction of the matrix Green function in the Nambu representation.rnThe expression for In (i:) and C;J is obtained for a superconductor with anrnarbitrary degree of anisotropy of the superconducting order parameter, ranging fromrnisotropic s-wave to d-wave and including anisotropic s-wave and mixed (s+d)-wavernas particular cases. The universal dependence of (i:) on 'P (a factor proportionalrnto ~, where T is the total relaxation time) and (:.) on Ii or 'P for a given value ofrnX (a coefficient for anisotropy of the order parameter) is shown in different plots forrndifferent casesrnKey words: AG-equation, Superconducting transition temperature Te, Isotope effectrncoefficient, Impurity effect, Disorder (defect) effect.