Data on 1420 high-standard rugby union players measured between 1905 and 1999 were collated to chart the evolution of body size and shape in rugby union football. Individual data were available for 843 players. Where only summary statistics were presented, Monte Carlo simulation was used to generate pseudo-data. Anthropometric variables included height, body mass, body mass index (BMI) and somatotype where available. The rates of increase in body mass (2.6 kg per decade) and BMI (0.4 kg x m(-2) per decade) were well above those of the general population of young males. The increase in height (1.0 cm per decade) was comparable to the secular increase. The increases in body mass and BMI since 1975 have been three to four times those between 1905 and 1975. Since 1975, players have been less endomorphic (-0.3 units per decade) and less ectomorphic (-0.4 units per decade), but much more mesomorphic (+1.1 units per decade) than before. There is a close association between body size and success. Final ranking in the 1999 World Cup showed significant correlations with the average mass of the squads.