Multiple sclerosis (MS) was first reported in Cuba in 1965. The most frequent appearance is observed in the first six months of the year.To determine the seasonal distribution and evolving forms of MS patients diagnosed with the disease between April 2004 and November 2007.Twenty-one patients with suspected MS and 42 outbreaks were studied. Patients were classified according to Lublin and Revingold's criteria for clinical forms and according to McDonald.Most patients were classified in outbreak and remission and only two patients classified as primary-progressive multiple sclerosis. The higher number of outbreaks occurred in the first two quarters of the year.It is recommended to study further weather variables that may be related to the emergence of these outbreaks in our environment.