The significance of various cognitive and psychosocial factors in the development, progression and persistence of chronic low back pain (CLBP) is well demonstrated. However, only a few studies have addressed CLBP patients' cognitive representations or beliefs about their disease and its treatment. The present study aimed to: (1) describe the illness and treatment beliefs of patients with CLBP, e.g., expected timeline, controllability or treatment related concerns; and (2) explore the relation of these illness and treatment beliefs to individual-, disease- and interaction-related variables. We conducted a cross-sectional survey with N = 201 patients at four inpatient rehabilitation centers. The characteristics of illness and treatment perceptions were analyzed using descriptive statistics. Multiple regression analysis was used to test the associations with disease-related, individual-related and interaction-related variables. The results demonstrated large inter-individual variability in the illness and treatment perceptions among patients with CLBP and pointed to several associations with disease-related variables, patients' personal characteristics and interaction experiences. The variables most strongly related to individuals' perceptions were those reflecting disease severity and individual disease experience. Further research is needed on CLBP patients' illness and treatment perceptions, and these personal disease experiences should be considered when designing new treatment approaches.