Hops in the brewing process are important for the chemical and sensorial quality of beer. Hops give to the beer bitterness (due to the presence of humulones and lupulones), natural antioxidants (due to the presence of polyphenols) and flavor (due to the presence of volatiles and essential oils). In this paper, we present, for the first time in Portuguese, a critical and comprehensive review about the phytochemistry of hops and the relationship between hop chemistry and the brewing process.