Objective Psychotherapy for hypochondriasis has greatly improved over the last decades and cognitive‐behavioral treatments are most promising. However, research on predictors of treatment outcome for hypochondriasis is rare. Possible predictors of treatment outcome in cognitive therapy (CT) and exposure therapy (ET) for hypochondriasis were investigated. Method Characteristics and behaviors of 75 patients were considered as possible predictors: sociodemographic variables (sex, age, and cohabitation); psychopathology (pretreatment hypochondriacal symptoms, comorbid mental disorders, and levels of depression, anxiety, and somatic symptoms); and patient in‐session interpersonal behavior. Results Severity of pretreatment hypochondriacal symptoms, comorbid mental disorders, and patient in‐session interpersonal behavior were significant predictors in multiple hierarchical regression analyses. Interactions between the predictors and the treatment (CT or ET) were not found. Conclusions In‐session interpersonal behavior is an important predictor of outcome. Furthermore, there are no specific contraindications to treating hypochondriasis with CT or ET.