The Meruliaceae are a family of fungi in the order Polyporales. According to a 2008 estimate, the family contains 47 genera and 420 species., Index Fungorum accepts 645 species in the family.
The family was formally circumscribed by English mycologist Carleton Rea in 1922, with Merulius as the type genus. He also included the genera Phlebia, Coniophora (now placed in the Coniophoraceae), and Coniophorella (now considered a synonym of Coniophora). His description of the Meruliaceae was as follows: "Hymenium spread over veins, anastomosing pores, or quite smooth; edge of veins or pores fertile." Several genera formerly classified in the Meruliaceae were moved to the family Steccherinaceae based on molecular evidence.
Meruliaceae species are crust-like or polyporoid, and often have a waxy appearance when dry. Their hyphal systems are monomitic (containing only tightly arranged generative hyphae), and these hyphae have clamp connections. The spores are smooth, thin-walled, and hyaline (translucent). Cystidia are often present in the hymenium. Although rare, some species have a dimitic hyphal system (with both generative and skeletal hyphae). Meruliaceae fungi cause white rot.