Acute lymphoblastic leukemia (ALL) is an uncommon but highly fatal disease in adults. We used period analysis to data from the Surveillance, Epidemiology, and End Results (SEER) database to disclose changes in outcomes for patients diagnosed with ALL in the United States in the 2 decades between 1980-1984 and 2000-2004. Major improvement in survival was observed for patients less than 60 years of age. Improvement in survival was greater for women than for men, but was significant for both genders. The greatest improvement was seen in patients aged 15 to 19, in whom 5-year relative survival improved from 41.0% to 61.1%, and 10-year survival improved from 33.0% to 60.4%. Lesser but significant improvements were seen for age groups 20-29, 30-44, and 45-59. Survival for patients aged 60 and over remained essentially unchanged at levels around or below 10%, respectively. Survival has improved for patients with ALL over the time period studied, but treatment of older patients remains a difficult issue.