Evidence for a secular change in heights and weights of adults of 13 populations in Papua New Guinea was sought by comparing data collected at two different times, using three types of source. These are: (1) values obtained from the literature; (2) previously unpublished measurements made by author; and (3) data found in the research notes of A.C. Haddon, and which were collected between 1897 and 1914. An increase in heights and weights has taken place in some, but not all, populations examined, whilst a decrease in adult body size has taken place in a smaller number of groups.