ObjectiveTo explore the efficacy and safety of ketogenic diet (KD) in the treatment of drug-resistant epilepsy in children with malformations of cortical development (MCD). MethodsThe clinical data of 10 children with drug-resistant epilepsy caused by MCD treated in the Epilepsy Center of Children's Hospital affiliated to Shandong University from May 2021 to February 2023 were analyzed retrospectively. All of them received classical KD treatment for the first time. The patients were followed up at 1, 3, 6 and 12 months after KD treatment. The clinical efficacy was evaluated by Engel grade and the adverse reactions were recorded at the same time. ResultsThere were 10 patients in this study, including 5 males and 5 females. The age of onset was 0.2~36.0 (10.3±11.1) months, 2.0~31.0 (9.7±8.5) months, and the age of starting KD was 3.0~50.0 (20.0±15.7) months. Cranial imaging showed that there were 2 cases of hemimegalencephaly, 1case of lissencephaly, 1 case of pachygyria combine polymicrogyria, and 6 cases of FCD,3 had gene abnormality (2 cases of DEPDC5 gene, 1 case of ARX gene). All children had different degrees of developmental retardation before KD treatment. The antiseizure medications taken before KD treatment were 2.0~5.0 (3.2±0.9). 5/10 (50%) children had a >50% reduction in seizure frequency at 3 months on the diet, 2/10 (20%) children had a seizure free response. The rate of development improvement was 50.0% (5/10) at 3 months. 5 cases had mild adverse reactions (50%), including 1 case of hypokalemia and 4 cases of gastrointestinal reactions, all of which were relieved after the reduction of the proportion of KD diet. None of the children stopped using KD. ConclusionKD therapy is a safe and effective method for the treatment of drug-resistant epilepsy in children caused by MCD, and some children can improve their developmental level.