Introduction: Congenital facial paralysis (CFP) can be classified into two groups by etiology: 1) conditions that are acquired during or soon after birth and 2) developmental disorders. Only about 10% of CFP is due to developmental disorders and this occurs in isolation or as a part of a recognized syndrome. Case 1 was a 7-month-old girl who was admitted for persistent right-sided facial paralysis noticed at birth, which was thought to be improving slowly. She was one of twins delivered by cesarean section at 36 weeks gestation and weighed 2340 gm at birth. There was no eventful antenatal or birth history. Brainstem evoked response audiometry(BERA) and otoacoustic emission (OAE) test detected a right-side sensorineural hearing loss (SNHL). When crying, her mouth angle deviated to the left and there were fewer wrinkles at the lateral angle of the right eye. When resting, she had mild ptosis of the right eye. The remainder of her otolaryngologic and systemic examinations was normal. There was no apparent dysmorphism. A nerve conduction study (NCV) showed a 75% degeneration ratio compared to the left side and electromyography (EMG) shows abnormal spontaneous activities. Constructive interference in steady state (CISS) brain magnetic resonance imaging (MRI) revealed hypoplasia of the right internal auditory canal and was possibly indicative of agenesis of the right facial and vestibulocochlear nerves. Case 2 was the younger twin sister of Case 1. Her birth weight was 2240 gm and there was no eventful antenatal or birth history. Like Case 1, she had an abnormal auditory screening test, with left-side SNHL on BERA and OAE tests. The otolaryngologic and systemic examinations were normal. Brain CISS MRI revealed hypoplasia of the left cochlear nerve, while the left and right facial nerves, left vestibular nerve, and right vestibulocochlear nerve were well delineated. Conclusion: This article reports twins with agenesis of the facial nerve and vestibulocochlear nerve accompanied by hypoplasia of the internal auditory canal in one sister and agenesis of the cochlear nerve in the other. This has not been reported in Korea.