The purpose of the present research was to study the descriptive anatomy of the gill of the mussel Lithophaga lithophaga. Mussels were collected from 2 sites in Antalya Bay, Turkey. Observations using stereomicroscopy and electron microscopy showed that the gills of L. lithophaga consist of homorhabdic filaments, a characteristic of the mytilids. The lamellae have cavities at their laterals in addition to their prominent ciliary structure on the frontal and lateral surfaces. The latero-frontal cilia extend in pairs, one attached to the other with a membrane and showing a composite structure. The ascending and descending lamellae are fused by fan-like cilia groups and form a food groove at their ventral margins. Scabrous blocks at the abfrontal edges of the ascending lamellae appear to function as food graters. The relatively large food particles captured by the mussel are ground into smaller pieces to be ingested. These morphological features of the gills of L. lithophaga can be used for comparison with those of other congeners or mytilids.