To assess the patterns of dietary (DS) and herbal supplement (HS) use in MS patients, compare use between MS patients and healthy controls and to identify potential interactions with drugs used to treat MS. This study included 279 MS subjects and 161 controls from a study of risk factors in MS. All patients received a neurological examination. All subjects provided responses to a standardized questionnaire administered during an in-person interview. A larger proportion of MS patients (82.1%) compared to controls (60.1%) used one or more DS regularly for at least 3 months (p < 0.001). There was a trend toward a higher proportion of MS patients (26.6%) versus controls (17.8%) who used HSs for more than 1 month (p = 0.038). The most common DS used after MS onset was a multivitamin (78.1%), followed by vitamin D (65.8%). Use of the majority of specific DSs increased significantly after MS onset compared to before. The proportion of controls and MS patients after MS onset who reported using an individual HS was generally similar. The most commonly used HS in patients after MS was evening primrose oil (40.4%) followed by cranberry fruit extract (35.2%). There was no evidence for associations with progressive disease course or with choice of disease-modifying treatment. Dietary supplements are used more frequently by MS patients than controls. Use tends to increase after MS onset compared to before, especially for DS. The use of HS by MS patients is only modestly greater than by controls.