Multiple sclerosis has been grouped into several main types. These include:   Relapsing-remitting MS — characterized by clearly defined attacks (relapses) followed by complete or partial recovery (remissions); most common form (75% at the time of diagnosis).

Primary-progressive MS — less common (10 to 15% at time of diagnosis), people with this type of MS have a nearly continuous worsening of MS from the beginning with no clear relapses or remissions.

Secondary-progressive — about half of people with relapsing-remitting MS start to worsen within 10 years of diagnosis, with possibility of increasing levels of disability.

Progressive-relapsing — relatively rare, combines attacks with steady worsening from the onset of the disease.

Benign MS — few attacks with long periods of remission and little disability after 15 years; about 20 - 25% of people who were diagnosed originally with relapsing-remitting MS have this type.