Aim: To measure the arch length of sides containing palatally displaced canines and to compare them with those of contralateral sides with normally positioned canines. Methods: The study sample consisted of 36 children 10 to 12 years of age with unerupted permanent maxillary canines who presented with palatally displaced canines, unilaterally, with respect to the maxillary lateral incisors. The palatal displacement was evaluated using the horizontal tube shift method with periapical radiographs, after the canine cusp tips were found to overlap their adjacent lateral incisors on panoramic radiographs. Arch length was measured on either side from a uniform point on the mesiolingual surface of the permanent first molar to a point on the dental arch that coincided with an anterior extension of the midpalatal raphae. The side that contained the palatally displaced canine was considered experimental, while the contralateral side was the control. The mean, standard deviation, range, and 95% confidence interval values were calculated, and the Student t test was carried out to obtain the P values for the arch lengths. Results: The mean arch length value from the experimental sides was 31.38 ± 1.98 mm (95% CI 29.30 to 33.45). The mean value from the control sides was 32.86 ± 2.28 mm (95% CI 30.48 to 35.24). Conclusion: There is a significantly high possibility of finding palatally displaced canines with respect to maxillary lateral incisors on sides with lesser arch lengths compared to the contralateral sides. World J Orthod 2010;11:e26–e28.