The treatment of older patients with acute lymphoblastic leukemia (ALL) is an unmet medical need. In Western countries, the population is aging, which means there will be an increasing number of older patients. However, in the past few decades, there has been little improvement in treating them, and few clinical trials specifically designed for older patients with ALL have been reported. Older patients with ALL have a significantly lower complete response rate, higher early mortality, higher relapse rate, and poorer survival compared with younger patients. This is partly explained by a higher incidence of poor prognostic factors. Most importantly, intensive chemotherapy with or without stem cell transplantation, both of which are successful in younger patients, is less well tolerated in older patients. For the future, the most promising approaches are optimized supportive care, targeted therapies, moderately intensified consolidation, and reduced-intensity stem cell transplantation. One of the most important challenges for physicians is to differentiate between fit and unfit older patients in order to offer both groups optimal treatment regarding toxicity and mortality risks, quality of life, and long-term outcome. Prospective trials for older patients with ALL are urgently needed.