This prospective study explored the contribution of illness representations and coping to cancer-related distress in unaffected individuals undergoing predictive genetic testing for an identified mutation in BRCA1/2 (BReast CAncer) or an HNPCC (Hereditary Nonpolyposis Colorectal Cancer)-related gene, based on the common sense model of self-regulation. Coping with hereditary cancer (UCL), illness representations (IPQ-R) and risk perception were assessed in 235 unaffected applicants for genetic testing before test result disclosure. Hereditary cancer distress (IES) and cancer worry (CWS) were assessed before, 2 weeks after and 6 months after result disclosure. Timeline (r = 0.30), consequences (r = 0.25), illness coherence (r = 0.21) and risk perception (r = 0.20) were significantly correlated to passive coping. Passive coping predicted hereditary cancer distress and cancer worry from pre-test (beta = 0.46 and 0.42, respectively) up to 6 months after result disclosure (beta = 0.32 and 0.19, respectively). Illness coherence predicted hereditary cancer distress up to 6 months after result disclosure (beta = 0.24), too. The self-regulatory model may be useful to predict the cognitive and emotional reactions to genetic cancer susceptibility testing. Identifying unhelpful representations and cognitive restructuring may be appropriate interventions to help distressed individuals undergoing genetic susceptibility testing for a BRCA1/2 or a HNPCC-related mutation.