Variation in eight morphological variables was analysed for the three New Zealand species of oystercatchers, Haematopus ostralegus finschi, Martens, H. unicolor, Forster, and H. chathamensis, Hartert. Within species, significant size variation was detected among age classes and between the sexes, making it necessary to use measurements only from adults and to treat the sexes separately in ensuing taxonomic comparisons. Analysis of morphological variation in hybridizing forms of H. unicolor suggests that gene exchange between the parental black and pied phases is extensive. Univariate and multivariate statistical analyses isolated three phenetic entities, consistent with three species as proposed in recent classification.