Worldwide, tonsillitis is very common. The most common etiology is cross-infection with bacteria and viruses. These cases are managed with antibiotics and anti-inflammatory drugs without any further investigation because the diagnosis is based on simple clinical examination. Usually, leukemia presents with bleeding, weight loss, lymphadenopathy, fever, and frequent infection. Tonsillitis is a rare first presentation of leukemia. We present 3 cases in which the diagnosis of leukemia was made on routine examination, and in 1 case diagnosis was suspected during tonsillectomy.