Two sandy beaches were studied in south - central Chile (ca., 39 degrees S), during 17 months to analyze the seasonal variability in population abundances and zonation of the most common species of the intertidal macroinfauna. The beaches displayed differences in mean grain size, Dean's parameter (a composite index of wave and sediment characteristics) and beach face slope. The peracarids Orchestoidea tuberculata Nicolet (Amphipoda, Talitridae), Excirolana braziliensis Richardson and Excirolana hirsuticauda Menzies (Isopoda, Cirolanidae), and the anomuran crab Emerita analoga (Stimpson) (Hippidae) were the most common organisms at both beaches, being E. analoga and E. hirsuticauda the top contributors to abundance. O. tuberculata tended to occur in higher abundance, either during autumn - early winter or late summer - early autumn; E. braziliensis was more abundant during summer - early autumn, while the abundances of E. hirsuticauda and E. analoga were quite erratic throughout seasons. In general, the temporal patterns of abundance did not show significant correlations with the beach physical factors considered. The species showed a clear pattern of zonation: O. tuberculata occurred in the upper beach levels (around the drift line); E. braziliensis occurrred in the mid - upper levels of the retention zone; E. hirsuticauda occurred throughout all the retention zone and also in the upper and middle levels of the resurgence zone, while E. analoga was mostly found in the swash zone and lower levels of the resurgence zone. Although, seasonal changes in the intertidal distribution was observed, it can be seen that each physical zone of the beaches is biologically distinct through seasons.