OBJECTIVE: Tooth agenesis is one of the most common anomalies in the development of the human dentition and may have wider associations in the development of the dentition including tooth size. This study aimed to compare mesiodistal crown dimension and arch widths between subjects with hypodontia and subjects without hypodontia (control group). MATERIALS AND METHODS: Dental casts were measured of 55 hypodontia patients and 55 patients with total permanent dentition (control group). Tooth agenesis was evaluated for hypodontia, excluding the third molars, from the panoramic radiograph. Mesiodistal crown dimensions were recorded by measuring all erupted teeth on study models with a digital Mitutoyo caliper (Mitutoyo U.K. Ltd, United Kingdom). RESULTS: Patients with hypodontia had smaller mesiodistal tooth dimensions than the control group, and this difference was statistically significant (p < 0.05) for all teeth in both genders. Upper lateral incisors, lower central incisors, and lower second molars showed the highest difference in tooth dimension. Also, the intercanine and intermolar arch widths in the hypodontia group were statistically significantly reduced (p < 0.05) compared with the control group. CONCLUSIONS: The findings indicate that the mesiodistal crown dimensions and arch widths are reduced in hypodontia patients. This should be taken into account when planning orthodontic treatment. CLINICAL SIGNIFICANCE: Congenital absence of permanent teeth has direct clinical implications. Early detection of the number of missing teeth and evaluation of the tooth size and arch width is of immense value in the planning and managing treatment with a multidisciplinary team approach to achieve an aesthetic and functional dentition and reduce the complications of hypodontia.