Constipation is a significant sociomedical problem, which can be caused by various reasons. In the diagnostic approach to patients with constipation, the following data are usually sufficient: History, complete physical examination (including rectal examination), and additional diagnostic tests. A colonoscopy is not a necessary diagnostic method for all patients with constipation. However, if patients have alarm symptoms/signs, that suggest an organic reason for constipation, a colonoscopy is necessary. The most important alarm symptoms/signs are age > 50 years, gastrointestinal bleeding, new-onset constipation, a palpable mass in the abdomen and rectum, weight loss, anemia, inflammatory bowel disease, and family history positive for colorectal cancer. Most endoscopists do not like to deal with patients with constipation. There are two reasons for this, namely the difficulty of endoscopy and the adequacy of preparation. Both are adversely affected by constipation. To improve the quality of colonoscopy in these patients, good examination techniques and often more extensive preparation are necessary. Good colonoscopy technique implies adequate psychological preparation of the patient, careful insertion of the endoscope with minimal insufflation, and early detection and resolution of loops. Bowel preparation for colonoscopy often requires prolonged preparation and sometimes the addition of other laxatives.