Background: The root canal length (RCL) estimates is an essential step for total endodontic therapy procedures. The aim of this study was to measure the RCL in a sample of extracted primary anterior teeth and compare the data obtained with the literature for educational and clinical purposes. Materials and methods: Seventy extracted primary anterior upper and lower teeth were selected according to the following inclusion criteria: absence of root resorption and/or internal root canal anatomy complications, and no previous root canal manipulation. The teeth were assigned to six groups: upper central incisors (UCI; n = 15), upper lateral incisors (ULI; n = 13), upper canines (UC; n = 20), lower central incisors (LCI; n = 6), lower lateral incisors (LLI; n = 3), and lower canines (LC; n = 13). RCL was measured by the direct method after insertion of a #15 K-file with a silicone stopper in the root canal until the root apex and measuring with a millimetre rule. Results: Mean RCL values (mm) obtained were UCI = 14.33 ± 1.69; ULI = 14.00 ± 1.63; UC = 16.07 ± 2.43; LCI = 15.41 ± 3.20; LLI = 15.00 ± 1.73; and LC = 16.38 ± 1.51. Conclusions: The RCL direct measurement method and the results obtained were in accordance with the literature reports and can be useful for educational purposes aiming at knowledge of dental anatomy and the clinical determination of root canal treatment viability and treatment of primary teeth, as RCL is one of the parameters for the indication/contra-indication of this therapy.