Purpose: The purpose of this study were to: (1) establish a facial soft tissue morphometric technique employing a 3-dimensional optical device; (2) evaluate its precision; and (3) determine the presence of diurnal variation in facial soft tissue morphology. Materials and methods: Ten volunteers were enrolled using a 3-dimensional optical measuring device, SURFLACER VMH-300F. Measurements were conducted in the morning, during the daytime, and in the evening. Two analyses, reproducibility of measurement through comparison between the two measurements in each group (morning vs. morning, daytime vs. daytime, and evening vs. evening), and diurnal variation through inter-group comparison (morning vs. daytime, morning vs. evening, and daytime vs. evening) were carried out. Results: The mean difference between two measurements in each group was 0.24 +/- 0.06 mm in the morning group, 0.25 +/- 0.08 mm in the daytime group, and 0.24 +/- 0.06 mm in the evening group. As to diurnalvariation, the difference was 0.38 +/- 0.07 mm between the morning and daytime groups, 0.39 +/- 0.03 mmbetween the morning and evening groups, and 0.40 +/- 0.04 mm between the daytime and evening groups. Conclusions: When facial morphology was measured at 3 different time points within a single day, themean error was 0.24 +/- 0.06 mm. Measurement at these 3 time points revealed no significant diurnalvariation in facial soft tissue morphology. This technique and its results are anticipated to contribute toquantitative evaluation of facial soft tissue morphology. (C) 2013 Asian AOMS, ASOMP, JSOP, JSOMS, JSOM, and JAMI. Published by Elsevier Ltd. All rights reserved.