This chapter focuses on cancer prevention media campaigns, concretely on the construction of the persuasive message. Methodologically, semiotic analysis is used, exploring the verbal and visual dimension of 19 international ads linked to the five most deadly cancers, in order to understand and deconstruct the message and the communication tactics used. The results reveal the diversity of resources and tactics. In the verbal dimension, it presents the use of rhetorical tactics (e.g., statistical and factual evidence and stimulation of emotions), the popular vocabulary, cues to action/motivational content, the phatic, poetic, and appealing functions, stylistic resources, credibility of the source, evocation of good causes, originality and distinction, anecdotal approach. In the visual dimension, it observes the use of three languages' functions, isotopy, stylistic resources, personalization, symbolical approach, polychrome, diversity of phenotypes, the credibility of the source, a pedagogical component.