The aim of this study was to review current constipation assessment scales and clarify (a) the nature of extant measurements and (b) the criteria contained in the measures. A review of relevant literature from inception to 2011 was extracted from PubMed, CINHAL, Cochrane, and MEDLINE databases by searching for the following key words: constipation, scale, measurement, questionnaire, and assessment. Eight scales were reviewed. The scales under review measured constipation from a subjective viewpoint. All measurement criteria included in 8 of the scales were arranged into 51 items and divided into 5 categories. Categories used to measure the severity of constipation were defecation difficulties, abdominal symptoms, emotional effects of constipation, self-treatment strategies, and individual characteristics. Original and suitable scales for the measurement of the severity of constipation based on the review were the Patient-Assessment of Constipation Symptoms scale and the Constipation Assessment Scale. The Patient-Assessment of Constipation Symptoms scale and the Constipation Assessment Scale are reliable, valid, original, and suitable scales to measure the severity of constipation for subjects.