In this paper I am concerned with risk-benefit analysis; that is, the comparison of the risks of a situation to its related benefits. We all face such situations in our daily lives and they are very common in medicine too, where risk-benefit analysis has become an important tool for rational decision-making. This paper explores risk-benefit analysis from a logical point of view. In particular, it seeks a better understanding of the common view that decisions should be made by weighing risks against benefits and that an option should be chosen if its benefits outweigh its risks. I devote a good deal of this paper scrutinizing this popular view. Specifically, I demonstrate that this mode of reasoning is logically faulty if "risk" and "benefit" are taken in their absolute sense. But I also show that arguing in favour of an action because its benefits outweigh its risks can be valid if we refer to incremental risks and benefits.