Objectives To investigate the effects of a number of variables on phoneme discrimination (PD) performance in children with sequential bilateral cochlear implants (SeqBiCIs) and compare PD performance between the 2 implantation sides and between children with bilateral cochlear implants (BiCIs) and their age-matched peers with normal hearing (NH). Design All participants completed the Auditory Speech Sound Evaluation Phoneme Discrimination Test. Study sample The sample included 23 children with SeqBiCIs as the study group and 23 with NH as the control group. Results A significant difference was found between the scores of the two groups under the CI1 and CI2 conditions (p = 0.001), CI1 and BiCI conditions (p = 0.002), and CI2 and BiCI conditions (p = 0.001). PD scores with CI1 significantly depend on age at CI1 and duration of bilateral use. PD scores with CI1 were significant predictors of PD performance with CI2. Duration of BiCI use was a significant predictor of PD scores with BiCI. Conclusions The age at CI1 and the duration of bilateral cochlear implant use were found to improve phoneme discrimination performance in children with a sequential bilateral cochlear implant. According to the success of the CI1, it is possible to predict the success of CI2 use.