We sought to identify (a) the change of incidence rates among gender from 1990 to 2002 from the LORSEP (Lorraine Multiple Sclerosis) population-based cohort, and (b) the role of gender as a predictive demographic factor of disability during the initial course of the disease among multiple sclerosis (MS) patients. The incidence rates of multiple sclerosis (MS) in Lorraine, France, have significantly increased in women, but not in men, from 1990 to 2002 but this increase in incidence of MS was not related to a better ascertainment of patients with mild disability. A total of 2871 MS patients were analyzed. For relapsing-remitting (RR) patients, a multivariate analysis showed that a shorter time to the assignment of an EDSS score of 3 and 4 was associated with the late onset MS, incomplete recovery from the first relapse and a high number of relapses during the first 5 years after the MS onset. Median times were not influenced by gender or by time between the first two relapses. The data were very different for the time between the assignment of scores of 4 and 6, since the median times were not influenced by any of the predicting variables.