Reactive lymphoid proliferations are found in the oral cavity under different presentations. Currently, there seems to be no classification scheme for lymphoid hyperplasias in the oral cavity, but they can be grossly organized into five different categories that provide a better understanding of their biological significance. (1) Reactive lymph nodes are uncommon in the oral cavity, most often appearing in the vestibular mucosa, while (2) mucosa-associated lymphoid tissue (MALT) is better appreciated as hyperplastic lingual tonsils. The dense lymphoid component of (3) lymphoepithelial cysts is well known, but a small epithelial component in some cases may cause misinterpretations. Different (4) chronic mucosal diseases affecting the oral cavity, such as lichen planus, lichenoid reactions, and leukoplakias, may demonstrate dense lymphoid aggregates in the connective tissue. The occurrence of idiopathic nonspecific lymphoid proliferations in the oral cavity can also be found, more commonly in the form of (5) follicular lymphoid hyperplasia, a benign lymphoproliferative disorder. The microscopic appearance of these entities varies, but the cellular distribution usually reveals the normal organization of B and T lymphocytes. These features, combined with a careful clinical follow-up, usually lead to accurate diagnoses.