This exploratory qualitative study was undertaken to expand our knowledge of cancer patients' perceptions of supportive and unsupportive interactions with members of their social networks and the factors that lead them to evaluate certain kinds of support as helpful and others as unhelpful. Fifteen cancer patients were interviewed using a structured interview schedule. The interview focused on several aspects of the social support process, including types of helpful and unhelpful behaviours, perceived contingencies affecting the expression of supportive and unsupportive behaviours and appraisals of helpful and unhelpful interactions.