Background: Cognitive and behavioral changes in ALS are recognized as an integral feature of the disease. Moreover, recent studies have also highlighted prominent changes in language and social cognition. The Edinburgh Cognitive and Behavioral ALS Screen (ECAS) is designed to detect the specific profile of cognition and behavior changes in ALS and to differentiate it from other disorders. It is evident that the test is specific and sensitive for ALS related cognition and behavioral changes and has been adapted and used for many languages to avoid the fallacy of cultural differences. However cognitive and behavioral changes of Mongolian ALS patients have not been studied. Purpose: Our aim is to assess the behavior and cognitive characteristics of patients with ALS using the Mongolian version of the ECAS. Materials and Methods: The study was conducted by cohort design and questionnaire method. Using the ECAS-Mon, a 15— 20 min screen, containing an ALS-Specific score (ALS-SS) and an ALS Non-specific score (N-ALS SS), cognitive and behavioral changes of ALS were studied in 30 ALS patients (none with evident dementia), 7 carers and 60 healthy controls. The results were processed using the SPSS (USA, version 25.0) program. Descriptive tests were done as appropriate. According to Abrahams et al., all cut-off scores were determined by subtracting two standard deviations from the mean score. Non parametric Spearman's correlation was used to estimate correlations between age, education and the test parameters.The differences in categorical variables were analysed by Pearson's x2 test, the differences between quantitative variables were analysed by the Manny-Whitney U test. Whent the p value was less than 0.05, the statistical significance was considered. The internal reliability of the test was determined by Cronbach's alpha. Results: Healthy controls’s (30 males, 30 females) mean age was 59.8 ± 14.4 and mean years of education was 12.5 ± 3.5. Patients’s mean age was 59.8 ± 11.0 and mean years of education was 11.4 ± 3.7. Data from healthy controls produced cut-off points of 86.8 for ALS-SS; 28.6 for N-ALS-SS; and 97/136 for ECAS total. Patients’s points were 53.7 for ALS-SS, 16.8 for N-ALS-SS, and 74/136 for ECAS total. The reliability of ECAS-Mon test was 0.91. The most prevalent deficit of cognition occurred in language functions followed by memory and fluency. Patients performed more poorly than controls, with significance levels at p < 0.001 for all domains of cognitive function. The dominant behavioral changes were apathy or inertia (39%), loss of sympathy or empathy (38%) and hyperorality and altered food preferences (31%) in ALS patients. Conclusion Mongolian ALS patients have decreased cognitive performances, specially memory performance compared to healthy control. The ECAS-Mon questionnaire can be used to detect ALS related cognitive and behavioral changes in Mongolian patients.