This study aimed at detecting a rough estimation of the prevalence of multiple sclerosis among citizens of Saudi Arabia. Methodology:It is a cross sectional study purposed to estimate the prevalence of multiple sclerosis in KSA in 2016. It involved 633 individual from the society of Saudi Arabia. Results and conclusion:Most of the respondents (68.1%)were female, Also most of them (47.1%) aged between (20-24) , (94.5%) of them were Saudi national, the largest proportion of them (34.4%) live in the eastern region, (69.8%) of them hold a university degree, and (57.7%) of the respondents are single. Also, we found out that (66.2%) of the respondents don't know if they have MS or not, while (64.1%) of them don't have relatives suffer from MS, as (24.3%) of the relatives who suffer from MS were cousins, and the most common suspicious symptom of MS was Fatigue Exhaustion as (6.8%) of the respondents have that symptom, also (96.4%) of the respondents don't suffer from immune diseases, and most of those who suffer from immune diseases (26.1%) suffer from eczema. Also, (86.1%) of the respondents don't suffer from Genetics diseases, while(18.2%) of the respondents who suffer from Genetic disease suffer from diabetes, and (71.7) of the respondents who suffer MS are females, while 49.1%) of the respondents who suffer MS aged between 25-35, (84.9%) of the respondents who suffer MS are Saudi national, and (39.6%) of the respondents who suffer MS live in the Objectives:-Central region, as (73.6%) of the respondents who suffer MS hold a university degree. The analysis illustrated that (64.2%) of the respondents who suffer from MS don't have relatives suffer from MS, and (33. ISSN: 2320-5407Int. J. Adv. Res. 4(12), 1581-1600 1582 (83.0%) of the respondents who suffer from MS don't suffer from immune diseases, and (22.2 %) of the respondents who suffer from MS and immune diseases suffer from rhumatic fever or erthymatosis, as (96.2%) of the respondents who suffer from MS don't suffer from Genetic disease, and (50%) of the respondents who suffer from MS and Genetics disease suffer from diabetes or hypertension. The results of analysis illustrated that there were statistically significant differences between those with and without MS as regard to age, nationality and the region (P<0.05), while there were no statistically significant differences as regard to gender, education and marital status(P>0.05). Also, MS was more prevalent between 25 and 30 years (49.1%), in Saudi nation (84.9%) and the central region (39.6%). Also, there were statistically significant differences at the level of significance (P <0.05), in the prevalence of MS in the relatives of the patients with and without MS in favor of no prevalence of MS in the relatives of (64.1%) patients with and without of respondents, We found that there were statistically significant differences between those with and without MS as regard to absence of suspicious symptoms of MS of Weakness in arm or leg, Loss of Balance and Anxiety (P<0.05), while there were no statistically sign...