Cyclin-dependent kinase-like 5 gene-related epileptic encephalopathy is gradually becoming better known in child neurology practice. The related gene mutations cause early infantile epileptic encephalopathy characterized by intractable epilepsy, severe mental retardation and, later, the development of Rett syndrome-like features. Herein, we report the first two Turkish cases of cyclin-dependent kinase-like 5 gene-related epileptic encephalopathy with novel mutations in exon 8, which is located in the catalytic domain of the gene.