The brown algae Padina concrescens is widely distributed in the northwestern Pacific México. We described the population of P. concrescens based on population parameters such as cover, density and size structure and reproduction at two levels tide at the intertidal area in the southwestern Baja California Peninsula. Monthly visits from January to December 2003 were done. Both cover and density were measured in situ by quadrants method. Samples were collected to obtain size structure and percentage of reproductive fronds. Our results show there is spatial variation in the population structure more than temporal. Thus, cover and density peak were at different months in each tide level studied, the lower tide level shows the high values in cover as well as density. The frond development was observed in height/width ratio this relation was consistent only in the low tidal zone. Size class distribution has consistently small size plants in both tide levels. Reproduction was seasonal in the tide channel but in both tide levels all the reproductive plants were tetrasporophyte. Our results suggest that this population is pseudoperenial and it strongly as a consequence of the intense competition in the intertidal zone.