Introduction: Teeth are readily accessible for examination and since no two teeth have similar morphology, they form an excellent forensic tool for sex determination. Tooth size standards based on odontometric investigations may be used in sex determination which forms one of the most important sub-disciplines of forensic odontology and is of paramount importance in medico-legal issues. Gender of an unknown person may be assessed by measuring the mesiodistal width of mandibular canine teeth as they exhibit sexual dimorphism. Aims and Objectives: 1. To record the mesiodistal width of mandibular canine teeth clinically, on plaster models and on intra oral periapical radiographs. 2. To compare and assess the reliability of each method. Materials and Methods: 100 patients belonging to Pondicherry population (50 males and 50 females) of the age group 15 to 25 years were randomly selected and the mesiodistal width of the mandibular canine teeth were measured clinically, on plaster models and on intra oral periapical radiographs. Result: In our study, comparing the three methods, statistically there was no significant difference among the three methods. There existed inter operator reliability in all the three methods as the t - value was not significant (p>0.05). Mean value of mandibular canine width in males and females on both sides was found to be statistically significant irrespective of the method used. Conclusion: From the present study, we conclude that the mandibular canine width greater than 7.3mm is suggestive of male and this helps in determining the gender of an unknown individual and it may be used as an important tool in forensic odontology. Keywords: sexual dimorphism, mandibular canine, mesiodistal width, radiomorphometric study, forensic odontology, odontometrics, pondicherry