Objective: Dermoid is a rare disease located in the head and neck and only sporadic cases were previously reported. Surgery with different operational paths is the best solution to the disease. We aimed to analyze the clinical characteristics and outcomes of surgical approach for treating dermoid originated from the middle ear and Eustachian tube. Methods: In this retrospective case series, four cases of dermoids of the middle ear and Eustachian tube, treated by endoscopic-assisted surgical approach were reviewed and analyzed. Results: Patients' ages ranged from 7 months to 16 years. All cases involved the middle ear, eustachian tube, and the parapharyngeal space. Postoperative follow-up ranged from 6 months to 11 years. No facial nerve paralysis was observed during or after surgeries. Treatment was efficient in the four cases, with no residual symptoms during post-operative follow-up. Conclusions: Dermoid of the middle ear involving the eustachian tube usually appears in children of early age. Surgical resection with assistance of endoscope has satisfying outcome for these cases.