Although some studies suggest that health locus-of-control beliefs are not affected by situational factors, others show that health locus of control is related to health status, indicating that this psychological construct is not as stable as suggested. In this study, the stability of health locus of control during a hospital admission for a surgical operation is investigated. Although test-retest coefficients suggest stability, mean scores of the powerful others health locus-of-control belief show an increase during hospital stay, and a decrease afterward toward the original level. Furthermore, this study shows that patients with fewer hospital experiences have a greater increase and decrease than patients with more hospital experiences. Under certain circumstances, health locus-of-control beliefs can be temporarily affected by situational factors.