Petrographic analyses of Lanaittu Sandstone (middle-upper Campanian, Eastern Sardinia, Italy), recovered from a geognostic well cored in 1989, permit reconstruction of the paleogeography of this area. The analyses were conducted in 1994 at the Geoscience Department of the University of Padova by Stefano Sanchetti using a Carl Zeiss Winkel-Standard Optical microscope with KPL W 12.5X oculars. The magnifications of the objectives were 5x, 10x, 25x, and 40x. At least 200 lithic grains have been identified in selected samples, and the results have been grouped into four categories: Metamorphic rock fragments (M), Plutonic rock fragments (P), Volcanic rock fragments (V), and Sedimentary rock fragments (S). The lithic fragments consist predominantly of plutonic, gneissic, and low-grade metamorphic rocks with rare carbonates and other sedimentary components.