Cell interactions with biomaterials are affected by surface topographic and chemical cues. Although it is well-known that nanometrical grooves/ridges structure modulates cellular spreading, elongation, and alignment, the combinational influence of surface topographic and chemical cues is not well studied. In this study, nano-textured silicon substrata with parallel ridges of 90, 250, or 500 nm wide, separated by grooves with equal width, were fabricated by electron beam lithography and dry etching techniques. Osteoblast-like cells, MG-63, were cultured on the patterned substrata with or without pre-adsorption of fibronectin. The cell morphology was imaged by scanning electron microscopy, and analyzed by image software. We found that FN coating initially modulated cellular spreading, length, and orientation on all types of grooved surfaces. However, after 24 h of culture, the cell morphology was not affected by FN coating on the 250-nm and 500-nm surfaces, while FN decreased cell alignment on the 90-nm surfaces. Our results suggest that surface chemical cues influence the initial cell-substratum contact, while the long-term cellular morphology is dictated by surface topographic cues.