Pollen morphology of the Pyrolaceae and Monotropaceae reinforces the view that the Pyrolaceae and Ericaceae are closely related and that the Monotropaceae should be treated as a distinct family. It further supports the separation of Moneses uniflora and Orthilia secunda from the genus Pyrola, and in the Monotropaceae it suggests a realignment of species within the Hypopitys-Monotropa complex. The Pyrolaceae as aligned by Schultze-Motel (1964) constitute a diverse group consisting of two subfamilies Pyroloideae and Monotropoideae, the latter largely saprophytic. Others have reduced one or both taxa to subdivisions of the Ericaceae, either as the tribe Pyroleae (Bentham & Hooker, 1873), or as the subf. Monotropoideae with the Pyroleae included in the subf. Arbutoideae (Copeland, 1941, 1947). A palynological study was made to determine if pollen morphology, a relatively unused attribute, might better characterize the affinities of the taxa involved. Erdtman (1952), largely following the systematic treatment of Drude (1889), described the pollen of 15 species representing eight genera. According to him, species of Pyrola L. have pollen united in tetrads with individual grains 3-colporate; pollen of Chimaphila umbellata Nutt. is in tetrads with apertures not always sharply delimited; pollen of Moneses uniflora (L.) Gray also is united in tetrads in which individual grains are 3-colp(oroid) ate; and Ramischia secunda (L.) Garcke [=Orthilia secunda (L.) House] has single grains which are (2-) 3colporate. In the Monotropoideae, Erdtman described pollen of Monotropa hypophegea Wallr. as (2-) 3-colporate, Pleuricospora fimbriolata Gray as (3-) 4colporoidate, Pterospora andromedea Nutt. as 4 (-5)-colporoidate, and Sarcodes sanguinea Torrey as 4 (-5)-colpate. Erdtman utilized Copeland's (1938) description of Allotropa virgata Torrey & Gray which was noted as three-grooved. Copeland (1934, 1935, 1937, 1938, 1939, 1941, 1947), in an extensive anatomical and systematic study of the tribe Pyroleae and subf. Monotropoideae, included a brief description of pollen of various genera. In his treatment of the Pyroleae (1947), he recognized four genera with the pollen grains of Ramischia Opiz (=Orthilia Raf.) solitary and tricolpate, those of Chimaphila Pursh in easily disrupted tetrads, those of Pyrola united in tetrads with the wall of each individual grain "marked by three half-grooves, continued as half grooves on the three as