The long‐term effects of limpets on a marine biofouling community were studied. Each of six 20 cm2shipping‐steel panels was artificially colonized by 15Patella caerulealimpets transplanted from intertidal rocks. Six other panels served as controls. The panels were hung at 1 m and 5·5 m depth from a pier in an Israeli port, and fouling was allowed to occur for 8 months. During winter, when fouling recruitment was low, the limpets reduced the 84%‐90% cover of biofouling to 1 %‐3%, and barnacle density from 2·6–3·8 to 0·7–0·8 individuals·cm−2. With the commencement of the spring surge of fouling recruitment, the controlling effects of the limpets steadily declined, but they continued to check the development of the high‐mass bryozoan cover. The decline was due to a feed‐back loop; heavy settlement of barnacles brought about an initial reduction in control that resulted in increased barnacle sizes and density. This also induced accelerated mortality among limpets, bringing about a further increase in barnacle density.