Objectives: Tooth size standards based on odontometric investigations can be used in age and sex determination in forensic investigations and natural disasters such as tsunami, earthquakes etc. where bones are frequently fragmented. In such cases, mandibular canines are found to exhibit the highest degree of sexual dimorphism. This study aimed to assess the usefulness of mandibular canine for sex identification. Methods: The present study was conducted based on measurements of mandibular canine teeth of 160 students (80 males and 80 females; aged 17–24 years) in Kathmandu University, Dhulikhel, Nepal. Results: Mandibular canine index for right and left canines was found to be significantly different in males and females. The identification of sex correctly using right mandibular canine index was 53.75% in males and 41.25% in females; and using left mandibular canine index was 61.25% in males and 38.75% in females. The sex can be predicted correctly using a mandibular canine index: being higher in males (57.5%) than females (45.62%). The mean mesiodistal width of the right and left mandibular canines and intercanine distance were significantly greater in males than females. Sexual dimorphism in right mandibular canine was higher (8.29%) than that of the left mandibular canine (6.12%). Conclusion: Sex can be predicted correctly using mandibular canine index. Right mandibular canine teeth are more sexually dimorphic than left. This may be influenced by gender, heredity, cultural, environmental and racial factors mostly influenced by Y chromosomes.