Spatial distribution patterns of two small serranids, Serranus scriba and S. cabrilla, have been investigated in June 2001 in northeastern Sardinia (Tyrrhenian Sea, Italy). Density and size of both species were estimated by visual census on shallow (5-7 m) rocky reefs constituted by different mineralogical types (granites vs carbonates), at different locations (several kilometres apart from each other) and sites (hundreds of metres from each other). Serranus scriba was significantly more abundant on granite rocks (where it also showed a greater frequency of large specimens) than on carbonates, while S. cabrilla displayed opposite patterns.