Introduction: Sexual dimorphism is one of the most important implications in forensic investigations and anthropological studies. Teeth are becoming a good source of material for gender determination. The canine is the most preferred tooth for gender determination because the canine is the strongest tooth in the oral cavity. Objectives: To investigate sexual dimorphism in permanent mandibular and maxillary canines of a Sri Lankan Sinhalese population, and to ascertain the most suitable dimension (labiolingual, mesiodistal and crown height) to determine the sex of an individual. Materials & Methods : The study was conducted using 384 dental casts (Males 192, Females 192) aged between 18 and 25 years in a sample of the Sri Lankan population. According to a selection criterion, casts were selected using a convenient random sampling technique. Mesio-distal, Bucco-lingual and Crown height of all the canines in the casts were measured using a digital vernier caliper accurate to 0.01 mm. Results : Statistical analysis was performed using Minitab 17 and SPSS (Version 21). Unpaired sample t-test, paired sample t-test and point-biserial correlation were used for data analysis. The present study revealed that males show larger mean dimensions of canine teeth than females. Out of all four canines, mandibular canines show highly consistent results for sexual dimorphism. Further, crown height is the best measurement to evaluate sexual dimorphism. Conclusion : It can be concluded that out of all the four canines, mandibular canines show highly consistent results for sexual dimorphism. Moreover, crown height is the best measurement to evaluate sexual dimorphism, in identifying an unknown .