Objective: Dental development is a useful method for age estimation. Although third molar eruption is commonly used to estimate age in Uganda, it is reported to be unreliable because of external influences. The more reliable radiographic techniques have inter-ethnic differences but data from sub-Saharan Africa are limited regarding estimating age in young adults. This study, therefore, aimed at determining the accuracy of Demirjian’s classification of the lower third molar, a common dental age estimation method, in estimating key ages in a Ugandan population using Ugandan references. Dental records of 1021 Ugandans aged 10-22 years were assigned to two groups; reference and test. The reference data was retrieved from a database of a previous bigger research project. Results: The overall sample population comprised of 514/1021 (50.3%) males. The mean age was 15.8 (3.6) years. No significant sex differences in dental age were established in the reference sample (520 records). Accuracy values (area under the curve) at the 12-, 14-, 16- and 18-year-cut-offs were between 0.83 and 0.90 using the test sample (501 records). The results suggest that Demirjian’s classification of the lower third molars is a useful method for age estimation in the young urban Ugandan population in the 10-22-year age-group.