Generally, width measurements of MD and BL provided more accurate results in sex determination than diagonal measurements. Thus, diagonal measures should be done only if there are difficulties in taking width measurements. Certain types of tooth rotations, crowding, and orthodontical abnormalities may make width measurements difficult. Taking diagonal measurements is always more difficult and requires more attention. If the compass is not placed correctly, measurements will be inaccurate. The author suggests that in certain cases diagonal measurements may be used to support width measurements. Sixty upper and lower jaw dental models that belonged to 30 males and 30 females were used in the study. These samples were from among high school students in Istanbul, Turkey. The inclusion criteria included fully developed teeth, no fillings or extractions, no crowns or orthodontic apparatuses, and no orthodontic abnormalities that could affect the measurements. Upper and lower jaw impressions were taken with alginate material, which was followed by the preparation of models by dental stone. This article describes the procedures used in taking teeth measurements from the models. 6 tables and 26 references