A review of 93 patients with ulcerative colitis revealed that in 47 (50.5%) symptoms first appeared between 21 and 30 years of age-“early-onset”-and in 26 (27.9%) at the age of 51 years or above-“late-onset.” Proctocolitis was more common in late-onset patients (p=0.077) and in males of both age groups (p=0.002). Extensive colitis was significantly more common in females (p=0.002). Patients with late-onset proctocolitis had more bowel movements/day and liver involvement than patients with early-onset disease. The first episode of proctocolitis was more protracted and the ensuing remission of shorter duration in late-onset patients. Most patients with earlyonset disease improved on steroid enemas, whereas most patients with late-onset disease required systemic corticosteroid therapy (p=0.0028). Female patients with earlyonset proctocolitis tended to be more severely afflicted than males, with an increased incidence of weight loss, leukocytosis, increased erythrocyte sedimentation rate (ESR), and need for systemic corticosteroid therapy. We conclude that late-onset uicerative colitis is distinct from early-onset disease in its relative refractoriness to therapy and its predilection for distal colonic involvement.