Literatures show sign language is a fully fledged language that can be employedrneffectively to teach the contents of a curriculum as spoken language. Though thernuse of sign language in education makes sense educationally, linguistically andrnpsychologically there are many grievances in the practices. In many parts of thernworld, sign language is seldom used in formal education. On the other hand,rnwhen signing is employed, it is either in the form of contact sign language or anrnartificially constructed manual in which sign codes for a spoken language,rnmostly.rnIn view of that, this research has attempted to examine sign language use asrnmedium of instruction in primary classes of Mekanissa School for the Deaf. Torndeal with this, the study employed a case study research technique. The datarncollected through 20 classroom observations, individual interviews with 7rnteachers, 10 students, 10 parents and 3 officials as well as several documentrnanalyses. Those data were examined and presented based on their themes inrndetail following narrative analysis method to achieve the purposes.rnAccording to the findings of the study, the Deaf communication approachrndominantly employed in primary classes of Mekanissa School for the Deaf isrnSimCom which is considered as best method by the teachers. Signed Amharicrn(Manual Codes for Amharic) is the principal MOI, while written and spokenrnAmharic served in few classroom activities. Unfortunately, the natural EthSLrnrarely employed as it is in many countries in the world. On the other hand, bothrnthe teachers and the students exhibited incompetency to make use of the signedrnlanguage in the classes besides their unconvinced attitude to utilize the naturalrnsign language as capable instrument of education. The classrooms and theirrnfacilities also found to be unsuitable to sign medium.rnThe challenges that hinder the effective utilization identified as they are relatedrnto improper proficiency of the teachers, students and the language itself, negativernattitude of the users, poor classroom facilitation, material unavailability and lackrnof clear policies. On the contrary the manualist philosophy the school advocatesrnand sign language training programs of the school appeared to be opportunitiesrnfor further improvements.rnGenerally, using sign language as MOI has several drawbacks in the cases.rnHowever, considering its benefit for Deaf learners, the research suggested tornpersist on using it along with conducting researches to improve the drawbacks inrnthe practices.