Congenital dermal sinus(CDS)is a rare entity of spinal dysraphism, caused by the focal failure of disjunction leading to adhesion between the cutaneous and neural ectoderm. Some reports found that tumors, such as dermoid and epidermoid cysts, meningitis and subdural abscess are often complicated by CDS. A 1-year-old girl was referred to our department for CDS with a dermoid cyst complicated by brain and subdural abscesses. Diffusion weighted imaging and gadolinium-diethylenetriamine penta-aceticacid administration revealed ring-enhancing lesions, suggesting brain abscess, in the left temporal lobe, and subdural abscesses on the bilateral middle cranial bases. T1-and T2-weighted lumbar magnetic resonance imaging revealed CDS. With a preoperative diagnosis of CDS with brain and subdural abscesses, resection of CDS was performed after draining the brain abscess twice. The CDS extended into the spinal canal and it was completely exercised. We then performed sub-total resection of the dermoid cyst in the subdural space. Recent reports showed that dermoid cysts are related to CDS infection and deterioration of the infection, as seen in this case. Complication of dermoid cysts is an important consideration during CDS treatment. While the mechanism of the development of brain abscess in CDS patients has been unclear, this rare but important case revealed the mechanism to be the direct spread of inflammation via CDS.