Female Magellanic Penguins (Spheniscus magellanicus) fought for the best quality nests, mainly before egg laying. Female fights (n = 47) were longer than male fights (n = 138), but less frequent and less intense as indicated by the number of flipper hits and length of cuts. Female winners occupied the disputed nests, and losers usually moved to nests of lower quality. Losers subsequently fledged fewer chicks than winners. Female winners were in better body condition, were not significantly larger, and were the owners of the nest as indicated by previous season attendance at the nest.