The present study aims to evaluate the use of Montessori Method for teaching Mentally Retarded Students (MRS) based on the opinions of special education teachers. Opinions of special education teachers on the use of Montessori Method for teaching MRS were analyzed based on the following criteria: gender of special education teachers, whether they are informed about Montessori Method, whether they are trained about Montessori Method, being employed in an educational institution having adopted Montessori Method, their bachelor degree, their seniority and length of service, the duration of their service in a special education institution, type of the special education institution they are working for. Furthermore the opinions of the special education teachers were collected on following issues: the comparison of the effect of Montessori Method on people of normal intelligence and people with MR, practicability of Montessori Method in Turkey, student-centered educational practices, setting the students free for their choices, presence of older and younger students in the same classroom. Quantitative and qualitative approaches were used together in the survey model of the research. Participants of the study were composed of 163 special education teachers working with students who have mental retardation in special education institutions and special education and rehabilitation centers affiliated to the Ministry of National Education. Of the participants, 108 were male and 54 were female. Of the special education teachers, 109 have been working for 1-5 years; 23 have been working for 6-10 years; 15 have been working for 11-15 years; 16 have been working for 16 years and more. Of the teachers, 36 have been working for mild special education classrooms; 38 have been working for independent Special Education Schools; 13 have been working for Special Vocational Schools; 23 have been working for moderatesevere special education classrooms and 64 have been working for Rehabilitation Centers. Questionnaire developed by researches for practicability of Montessori Method for teaching MRS by special education teachers was used as data collection tool. Cronbach’s Alpha was 0,831 according to reliability study conducted with 258 people for the questionnaire. Researchers visited the schools and met the teachers and questionnaires were filled by participants. Qualitative data of the research was analyzed through descriptive approach. Data were analyzed for quantitative data and they were determined to be normally distributed. Afterwards, of the parametrical tests, t test, Anova and Tukey’s test were used for analysis. According to research results, special education teachers have moderate opinions about the use of Montessori Method in teaching MRS. Factors such as special education teachers’ being trained about Montessori Method, being informed about Montessori Method, being employed in an educational institution having adopted Montessori Method and the duration of their service as special education teacher did not create any difference in the opinions of teachers on practicability of Montessori Method in teaching MRS. Female special education teachers think that Montessori Method may be adopted in teaching MRS more commonly. Opinions held by the teachers graduated from the department of child development are more positive than the opinions of teachers graduated from the department of special education for using Montessori Method in teaching MRS. There is difference in the opinions of the teachers about the use of Montessori Method in teaching MRS according to the type of educational institution they are working for. Accordingly, teachers working in special-education classroom within a regular school have more positive attitudes than teachers working in independent special education institutions, moderate-severe special education classrooms, rehabilitation centers and special vocational schools. The majority of the participants think that Montessori Method may be applied in Turkey for teaching MRS. Special education teachers approve walking freely around according to this method however they point out that presence of older and younger students in the same classroom may result in disciplinary problems. Participants indicate that Montessori education may be effective for people of normal intelligence.