The clinical presentation of ulcerative colitis at the moment of diagnosis is variable, and its clinical course is difficult to predict. It can range from a quiescent to a refractory chronic course that may require hospitalization and surgical procedures. It can also have complications such as colorectal cancer. In this review we discuss the role of demographic, clinical, endoscopic, histological and associated factors, which can help to predict the clinical course of the disease at the moment of diagnosis, and to individualize therapy according to this clinical risk. Accurate identification of patients with a newly diagnosed ulcerative colitis who are at high risk of an unfavorable outcome is still a challenge. However, an effective evaluation allows an early diagnosis, a timely and effective treatment.The clinical presentation of ulcerative colitis at the moment of diagnosis is variable, and its clinical course is difficult to predict. It can range from a quiescent to a refractory chronic course that may require hospitalization and surgical procedures. It can also have complications such as colorectal cancer. In this review we discuss the role of demographic, clinical, endoscopic, histological and associated factors, which can help to predict the clinical course of the disease at the moment of diagnosis, and to individualize therapy according to this clinical risk. Accurate identification of patients with a newly diagnosed ulcerative colitis who are at high risk of an unfavorable outcome is still a challenge. However, an effective evaluation allows an early diagnosis, a timely and effective treatment.