Objectives. To use hierarchical class analysis (HICLAS) in a case study to offer insight into the effect of exercise on aspects of functioning of a depressed patient.Methods. Based on a retrospective interview with a 32-year-old depressed male patient, immediately preceding discharge from the hospital, a HICLAS grid analysis of interactions between relevant situations in the hospital, including different treatment components, and emotional and behavioural reactions is described and explained.Results and conclusions. Although there is no support for a direct antidepressant effect of fitness training, the results reveal that fitness training embedded in a cognitive-behavioural treatment program, is associated with positive changes in other relevant aspects of the patients' functioning. This includes enhanced coping strategies, sustained efforts to continue activities, and improved awareness of physical well-being. Other therapeutic interventions and pharmacotherapy are associated with a more ambivalent reaction pattern of positive as well as negative emotional and behavioural characteristics. The present findings are discussed in light of the multidisciplinary approach to clinical depression. Furthermore, the application of intra-individual research methodology is highly recommended to complement more traditional research designs to investigate the effect of exercise on depressed patients, not least because new research hypotheses can be generated.