Growth is a trait linked to development of organisms and expressed as an increase of body size, and which can be described using sigmoidal functions. There are different growth models which are base don sigmoidal function, being some of them the logistic, Gompertz's and von Bertalanffy's. The purpose of this research wasto determine the growth between sexes in Hydrochoerus hydrochaeris using the logistic function y=a/(1+be-cx). Thus function allows a better visualization of what happens during growth. With this aim, it was studied a sample of 30 animals (11 males and 19 females) from 2 to 96 months. For each animal the following measurements were obtained: body length, withers height, head length, head perimeter and thoracic girth. Sampled animals were from 3 different farms in Fortul, (Arauca, Colombia), in 'piedemonte' area, and were managed under semi-extensive conditions. From statistical analysis it was observed that all variables were statistically different between sexes. It is concluded that growth in H. hydrochaeris is different between males and females, the former growing faster and more precociously, ending with bigger sizes.