Introduction: Dietary approaches to management of MS has been proposed for several decades, yet very little is known concerning dietary composition or adherence to specialized diets in people with multiple sclerosis (MS). Methods: We conducted a survey of participants in the North American Research Committee on MS (NARCOMS) registry assessing diet composition and the prevalence of 19 different diets. We characterized prevalence of different diets and compared diet composition with estimated intakes from the National Health and Nutrition Examination Survey (NHANES) survey respondents and across demographics and MS clinical characteristics. Results: Among the 7639 (68%) responders, 6990 provided sufficient information on diet to be included in the analysis. Compared to NHANES participants, responders tended to have comparable intakes of fruit, vegetables and legumes (mean [SD] 2.5 [1.0] servings/day) and whole grains (0.9 [1.3] servings/day) and consume less added sugar (NARCOMS: 9.7 [6.0] vs. NHANES: 18.5[13.5] tsp/day; P < 0.001) and more red meat (NARCOMS: 0.50 [0.47] vs. NHANES: 0.35 [0.97] servings/day; P < 0.001). Of the 3120 (45%) participants who reported any history of following a specific diet, commonly-followed diets were: low-sugar (n = 642), low-carbohydrate (n = 508) and low-calorie (n = 475). Those with no history of following any specific diet were more likely to have progressive MS, be more obese, have worse overall diet quality, not participate in physical activity and smoke (all P < 0.001). Conclusions: In this large survey, we found that diet composition in MS patients may vary by demographic and disease characteristics.