40 patients affected by Multiple Sclerosis, all in a worsening phase, have been treated with cicles of HBO since 1979. The therapy consists of a first cycle of dayly treatment (5 in a week) for a total of 10-15 sessions (90' at 2 ATA) and subsequently, according to the case, 3-5 sessions every 1-2 months, or 1 monthly treatment. Six cases did not showed improvements; among these, 4 have received adequate treatment, but in 5 cases the clinical picture do not worsen. The resting 34 cases (85%) had remarkable improvements, complete or near total recovery of one or more symptoms after the first cycle or the following treatments. Improvements or recovery of symptoms can be temporary or permanent along the period of observation (from 3 to 33 months). In 8 subjects the improvement were progressive after successive cycles. Cerebellar, sensorial, and sphincterial symptoms are the most susceptible of positive changes. Walking improvements, hand use normalisation and a better bladder control have allowed many patients a very satisfactory recovery of autonomy.