Breadfruit, a versatile tree crop predominately used for its nutritious and starchy fruit, is commonly consumed among West Indian people. Because of its seasonality and shortshelf life, there is a need for an economical method of extending its availability. One such process is through the production of breadfruit flour. However, detailed information is needed on the nutrient profile of the flour. More research is needed in order to determine whether there are cultivar differences; previous research has been limited to one un-named cultivar at one stage of maturity. The objective of this study was to determine the influence of cultivar and maturity on the yield and nutrient composition of breadfruit flour. Four breadfruit cultivars, Jackson Macca (JM), Kashee Bread (KB), Local White (LW) and Local Yellow (LY), growing in the germplasm collection of the University Field Station, Valsayn, Trinidad, were evaluated for flour yield and nutrient composition. The fruits were harvested at the immature and mature stages. The flesh was sliced 5 mm thick, dried at 60° C for 24 hours, milled and sieved (0.60 mm). Proximate analyses were done in triplicate and according to the AOAC methods (1990). There were no significant differences in the fresh weights of the four selected cultivars. However, there were significant differences (p<0.05) in yield, dry matter, ash, crude protein, ether extract, dietary fibre, carbohydrates, calcium, magnesium, and iron content of the breadfruit flours. Cultivar JM showed the highest yield (46.5±1.4%) in addition to the highest levels of crude protein (5.5±0.4 g/100 g), ether extract (1.6±0.1 g/100 g) and carbohydrates (71.7±0.3 g/100 g). There were significant differences between dry matter (91.8±0.3 g/100 g immature; 90.9±0.2 g/100 g mature) and carbohydrates (67.9±0.8 g/100 g immature; 69.9±0.4 g/100 g mature). This finding illustrates that as the fruit matures, there is an increase in moisture and in carbohydrate content. This increase may be partly due to metabolic water and the bulking up of starches and sugars within the fruit as it matures. The knowledge of the nutrient composition of breadfruit flour is necessary for the production of acceptable food products which satisfy the nutritional needs of consumers, leading to increased use of breadfruit and thereby contributing to sustainable agriculture and food security.