Endothelin (ET) is one of the biomolecules that play important role in orthodontic tooth movement which may contribute to the different rate of tooth movement between adolescents and adults. This study aimed to investigate the messenger RNA (mRNA) expression of endothelin-1 (ET-1), endothelin A (ET_A), and endothelin B (ET_B) receptors in human periodontal ligament (PDL) cells from adolescents and adults. The PDL cells were obtained from ten patients, which were categorized by age into 2 groups: adolescent group and adult group. The levels of ET-1, ET_A, and ET_B mRNA expressions were determined by quantitative polymerase chain reaction (qPCR). Expressions of ET-1, ET_Aand ET_B receptor mRNA in the adolescent group were significantly higher than in the adult group. (p = 0.025, 0.027, and 0.019 respectively). In summary, mRNA expressions of ET-1 and its receptors in PDL cells from adolescents were higher than adults but the role of the ET system on the different rate of tooth movement remained to be elucidated.