Sexual dimorphism in body size, body condition (body mass relative to body size), and relative head size was investigated on 1250 field-caught Python regius (Togo, western Africa). Sexual dimorphism was often undetectable in neonates. By contrast, sexual dimorphism was apparent for many traits in adults. Adult females were larger and had a higher body condition than males; they also had longer jaws relative to their body size. This suggests that females and males follow different growth trajectories from birth to adulthood. In support of this, neonate females had a higher postnatal growth rate than males. Fecundity was strongly correlated with body size in females; a larger body size may be favored by fecundity selection in this sex. Our data show that females mature at a large body size: 95 cm in snout–vent length (SVL). The estimated external parasite load (number of ticks) was higher in adult males than females, perhaps because males encounter more ticks during movements.