Chalcones are natural compounds found in plants, fruits and vegetables. This class of compounds has shown many biological activities including antioxidant, antimicrobial, anti-inflammatory, antifungal and antihypertensive, among others. In cancer, it has been reported that chalcones interfere in several points of the signal transduction pathways related to cellular proliferation, angiogenesis, metastasis, apoptosis and the reversal of multidrug resistance. The large number of research articles and patents related to chalcones is already an indication of their importance as a lead class of compounds. This article gathers recent efforts to elucidate the molecular mechanisms of action of chalcones, associated with their anticancer and anti resistance potential.