We present a unified approach for the exact bit-error-rate (BER) analysis of binary direct-sequence code division multiple access (DS-CDMA) systems operating over generalized frequency-selective fading channels. The approach is based on alternate representations of the Gaussian Q-function and the Marcum Q-function. Our results are applicable to systems employing RAKE reception with coherent maximal-ratio combining as well as noncoherent and differentially coherent equal-gain combining. The analyses assume independent resolvable fading paths which are not necessarily identically distributed nor even distributed according to the same family of distributions. The proposed approach gives new analytical expressions for BER under very general channel conditions, in addition to simplifying previously-known results both analytically and computationally.