Background: Trigeminal neuralgia (TN) is a well-recognized cause of facial pain in the general population, and multiple sclerosis (MS) accounts for some of these cases. However, the prevalence of TN in MS is poorly understood. We investigated the prevalence of TN and how often TN is the initial presentation of MS in a large MS cohort. Methods: In 2009, we surveyed participants in the North America Research Committee on Multiple Sclerosis Registry regarding TN, including date of onset and pharmacologic and nonpharmacologic treatments used. We estimated the frequency of TN and the frequency with which TN preceded the diagnosis of MS. We compared the demographic and clinical characteristics of participants who reported TN with those of participants who did not using descriptive statistics and logistic regression. Results: Among 8590 eligible survey respondents, the prevalence of TN was 830 (9.7%). Of these respondents, 588 reported the year when TN was diagnosed. The diagnosis of TN preceded that of MS in 88 respondents (15.0%), and the mean ± SD age at diagnosis of TN was 45.3 ± 11.0 years. The odds of reporting TN were higher in women and those with greater disability and longer disease duration. Pharmacologic treatments were used by 88.3% of respondents; 9.7% underwent surgical interventions. Conclusions: In MS, TN occurs frequently and precedes the diagnosis of MS in 15.0% of individuals. Given the frequency of TN in MS, further epidemiological studies and clinical trials to identify effective pharmacologic and nonpharmacologic therapies for TN in MS are warranted.