The study was concerned with the psycho-social consequences for married couples of multiple sclerosis being contracted by one of the partners. In particular, problems of social interaction and group identity were explored. In determining their mode of interaction with healthy people such couples can choose between normalizing, i.e. endeavouring to carry on their relationships with other people according to their pre-illness pattern, or of disassociating, i.e. turning away from former associates and seeking a new peer group among others with like affliction. In nearly every case husband and wife agreed on the choice of stratagem, a majority of the couples forming the sample opting for disassociation. Membership of the Multiple Sclerosis Society was much more usual among the disassociating couples than among those ‘normalizing’. The variables of age, sex, social class and severity of illness were not found to affect the mode of interaction, whereas place of residence and medical interest in them, as perceived by patients and their spouses, were influencing factors.