In this paper, the performance of a maximum-likelihood code acquisition technique is analyzed for slotted-mode preamble search in a CDMA reverse link. The probabilities of detection, miss, and false alarm are derived analytically for a frequency-selective Rayleigh fading channel by taking into account the fading characteristics of a received signal for both single and dual antenna cases. Numerical examples illustrate the effects of post-detection integration, fading rate, and antenna diversity on the code acquisition performance.