We present the fi rst 2 cases of cochlear implantation in Mongolia using “SONATA” type implant of “MED-EL” Company, Austria. CASE 1: A six years old, female had been diagnosed with bilateral congenital profound hearing loss and had been fi tted with hearing aids for 5 years and received little benefi t from her hearing aids and developed very poor speech and language, used lip reading and have had vocabulary of approximately 10 words. A radiological evaluation showed normal cochlea and auditory nerve. Cochlear implant team including speech therapists and audiologists based on the informed consent of patient’s parent decided that family able to participate in follow-up, speech habilitation programme. Patient implanted with SONATA of MED-EL on 4 August, 2009. Electrodes were inserted fully. After 10 days of switch on of the speech processor the patient showed signs of initial hearing of loud sounds. After 5 months of Auditory Verbal Therapy the vocabulary increased up to 50 words. Hearing, cognition and responses are increasing simultaneously. CASE 2: A 2 years old female. Congenitally deaf in both ears. Fitted with hearing aid for 3 months before the surgery and there was no benefi t from hearing aid. Physically and mentally healthy. Patient implanted with SONATA of MED-EL on 4 August, 2009. Electrodes were inserted fully. On 25th days of switching on of speech processor the patient showed initial hearing of loud sounds. Currently, after 5months of treatment her vocabulary is 2 short words and can recognize 4 syllabeles. She is very active, repeats actions and has open nature, feels comfortable with CI.