Haematological values were determined in 50 Rockhopper (Eudyptes crestatus), 19 Gentoo (Pygoscelis papua) and 12 Magellanic (Spheniscus magellanicus) penguins from various sites on the Falkland Islands. Adult Magellanic penguins had significantly lower haemoglobin (Hb) levels, packed cell volumes (PCV) and red cell counts (RBC) than adults of the other two species. Hb, PCV and RBC values were also lower in juvenile birds than in adults and lower in post-moult than in pre-moult adults. Comparison of findings in wild Rockhopper and Gentoo penguins with values obtained from captive birds showed slight but significant differences in Hb and mean cell haemoglobin concentration, and in the relative numbers of heterophils, lymphocytes, monocytes and eosinophils present.