Under projected climate changes, runoff and soil erosion processes are likely to become more severe due to the intensification of extreme precipitation events. In consequence of the expected increase of rainfall intensity and erosivity, grass cover is acknowledged as the most effective soil management practice adopted to reduce soil loss by runoff. The aim of this study was to verify the effectiveness of grass cover (GC) in preventing runoff and soil erosion in sloping vineyards with respect to conventional tillage (CT) and to seasonal pattern. Rainfall, runoff and soil loss from experimental farm of Vezzolano (NW-Italy) were recorded in two different periods. Results confirmed the effectiveness of GC, especially when high erosive events occurred in summer, while soil protective effect considerably decreased in autumn, thus pointing out the need to improve appropriate agronomic strategies to achieve better water and soil protection throughout seasons.