This study aimed to prospectively consider the effect of colonoscopy on patients?experiences of anxiety at 4 time points related to an initial colonoscopy, using a qualitative approach. The study involved a sample of 13 patients undergoing an initial colonoscopy at a public hospital and followed for 12 months. Four exploratory interviews were conducted with each participant: before the procedure, 1 week, 2 weeks, and 12 months after the procedure. Thematic analysis was conducted to summarize patients?responses. In these participants, colonoscopy was associated with stigma. The discussion of the procedure was perceived as stressful and embarrassing and led to anxiety. Irrational expectations regarding the procedure were also contributing to anxiety, as was a doctor-patient relationship based on unequal powers and lack of control. Before the procedure, fear of a serious diagnosis contributed to anxiety; however, postprocedure, an unclear or functional diagnosis also appeared to increase anxiety. Anticipating the preparation for the procedure was also reported as an important factor in preprocedure anxiety. A shift toward a biopsychosocial approach to healthcare, such as providing patients with a greater sense of control by participating in decision making, should be recommended as it may reduce anxiety.