Introduction. Corpus callosum abnormalities are complex, aetiologically diverse, and clinically heterogeneous conditions. Counselling parents regarding their causes and associated syndromes, and predicting the neurodevelopmental and seizure risk prognosis, is challenging. Material and methods. We describe the clinical characteristics, associated anomalies, and neurodevelopmental outcomes of children with agenesis of corpus callosum (ACC). Fifty-one neonates with ACC/hypoplasia of the corpus callosum were identified over a 17-year period, and their medical records were retrospectively reviewed. Results. Patients were classified into two groups depending on the presence or absence of associated abnormalities. The first group (17 patients, 33.4%) presented with isolated callosal anomalies. The second group included 34 patients (66.6%) with associated cerebral and extracerebral anomalies. We achieved an identifiable genetic aetiology in 23.5% of our cohort. Magnetic resonance imaging was performed in 28 patients (55%), and of these 39.3% had additional brain anomalies. During the study period, five patients died early in the neonatal period and four were lost to follow up. Of the 42 followed patients, 13 (31%) showed normal neurodevelopment, 13 (31%) showed mild delay, and 16 (38%) had a severe delay. Fifteen (35.7%) had epilepsy. Conclusions and clinical implications. We have confirmed that callosal defects are frequently accompanied by brain and somatic anomalies. Additional abnormalities were shown to be significantly associated with developmental delay and increased risk of epilepsy. We have highlighted essential clinical features that may provide diagnostic clues to physicians and we have given examples of underlying genetic disorders. We have provided recommendations about extended neuroimaging diagnostics and widespread genetic testing that may impact upon daily clinical practice. Paediatric neurologists may therefore use our findings to help base their decisions regarding this matter.