Problem Self-tracking—and of course also health-related self-tracking—has an influence on those who use it. This influence can (but does not necessarily have to) pose a threat to the autonomy of people tracking themselves. Argumentation Self-tracking can easily come into conflict with one of the three conditions for autonomy defined by Beauchamp, Faden, and Childress: voluntariness. Based on a distinction between different forms of manipulative influence—mildly controlling and substantially controlling—I will argue that health-related self-tracking often has a mildly controlling influence but (...) that it can also turn into a substantially controlling manipulative influence and even become coercive. Conclusion Substantially manipulative self-tracking and self-tracking that involves coercion is a violation of the condition of voluntariness set for autonomy. This risk of violating autonomy must be taken into account when assessing health-related self-tracking. (shrink)