Objectives : Event-related potentials have been suggested as an objective marker for brain functions in psychiatric disorders. This study was aimed to investigate the relationships between P300, the mismatch negativity (MMN), the loudness dependence of the auditory evoked potential (LDAEP), demographic and clinical variables including neurocognitive abilities in patients with schizophrenia. Methods : P300, the MMN, and the LDAEP were measured and the Korean Stroop color-word test (K-stroop test) and the Wisconsin Card Sorting Test (WCST) were performed in 43 patients with schizophrenia. The relationship of the latency and amplitude of P300 and the MMN as well as regression slope of the LDAEP with demographic and clinical variables were analyzed by t-test and correlation analyses for categorical and continuous variables, respectively. Results : After controlling for age, the latency of central (Cz) and parietal (Pz) P300 posivitively correlated with GAF at admission (Cz ; ${gamma}$ = 0.385, p = 0.047, Pz ; ${gamma}$ = 0.421, p = 0.029). The amplitude of parietal P300 correlated with the correction rate of the K-stroop test (${gamma}$ = 0.575, p = 0.002). In addition, the frontal (Fz) P300 latency tended to negatively correlated with the correction rate of the WCST (${gamma}$ = -0.371, p = 0.057). Conclusions : Our findings suggest that the values of P300 latency and amplitude might be correlated with GAF at admission and working memory measured by the K-Stroop test and the WCST. Meanwhile, the MMN and the LDAEP did not correlate with demographic and clinical variables. These results support the results of previous studies showing associations with P300 and impaired cognitive ability.