Photosynthetic responses to light have been examined in nine temperate rainforest species, including Nothofagus species from Australia and Chile, in order to correlate comparative light requirements with regeneration patterns and forest dynamics. Nothofagus gunnii (Hook. f.) Oerst. has the highest light requirements of the Australian Nothofagus species and this correlates with its failure to regenerate in closed forest. N. alpina (Poepp. et Endl.) Oerst. is the most shade-tolerant of the Nothofagus species examined in this study, and this result conforms with regeneration patterns observed in Chilean rainforest. The Australian species, N. cunninghamii (Hook.) Oerst. and N. moorei (F. Muell.) Krasser, and the Chilean species, N. obliqua (Mirbel) Oerst. and N. dombeyi (Mirbel) Oerst., have similar photosynthetic characteristics. Consequently, the comparative light requirements of the Nothofagus species described here do not explain differences in the dynamics of rainforests dominated by these species. Differences in the regeneration characteristics of co-occuring understorey and shade-tolerant canopy species appear to be more important determinants of the dynamics of these forests.