This article examines the illness experiences of patients with chronic myeloid leukemia (CML), focusing on dimensions that link the onset of the disease as a biographical disruption. This qualitative study was based on analysis of narratives by six patients 23 to 62 years of age who were users of the Brazilian Unified National Health System (SUS) and patients at a referral hospital for hematological care in Salvador, Bahia State, Brazil. The results reveal the experience of disruption in three categories: (1) the meanings of illness and CML as life-threatening, (2) physical and social disruption and stigmatizing experiences, and (3) the "before-and-after" perception of CML, focusing on changes in self, social relations, and daily life. The article concludes that the biographical, social, and health-system impacts (considering the cost of medication) update and extend issues such as access to treatment and confronting certainty and uncertainty, where patients struggle to draw on their everyday knowledge to deal with what is "known" about CML.