High, moderate and low stimulation rates of 1800, 800 and 400 pulse per second (pps)/channel, respectively, were used to test the effects of stimulation rates on the discrimination and identification of Cantonese lexical tones in 11 Chinese post-lingually deafened adults with cochlear implants (CIs). The subjects were implanted with the MED-EL Combi 40+ CI system. They were randomly assigned to each of the stimulation rate conditions according to an ABC design. In both the Cantonese lexical tone perception tests, the subjects reached the highest scores in the high-stimulation-rate condition, and the lowest scores in the low-stimulation-rate condition (P < 0.01). Post hoc comparisons between different stimulation rates did not yield consistent results. This study demonstrated that the maximum stimulation rate of 1800 pps/channel could be an 'optimal' stimulation rate and an informed choice of parameter for the benefit of Cantonese-speaking CI users in lexical tone perception.