Aim: Our study was aimed to determine both demographic and clinical data of patients with symptomatic West Syndrome (WS) and to monitor their neurocognitive development with Bayley Scales of Infant and Toddler Development Screening Test, third edition (Bayley-III) test. Materials and Methods: Fourteen symptomatic WS patients were included in our study. Clinical and demographic data, electroencephalogram (EEG) findings, treatment response, Bayley III developmental test results were recorded before starting the treatment (T0) and in the 12th months of the treatment (T1 and T12). Results: Patients had a significant increase in Bayley-III test scores in all areas at the end of one year (p <0.05). As the patients' EEGs improved, a statistically significant increase was observed in Bayley-III test scores in all areas (p <0.05). However, when the correlation between seizure control and the Bayley-III test scores were evaluated, there was an improvement only in the language area (p< 0,05); but there was no statistically significant difference in other brain areas (p> 0.05). Conclusion: It has been shown that the neurocognitive level gradually improves even in symptomatic type WS with effective treatment during the follow-up of the disease or with the improvement of the EEG findings and seizure control.