Leukaemias are malignant neoplasms that affect the bone marrow, compromising the production of functional blood cells. In Brazil, leukaemia is the 13th most frequent cancer and the most common among individuals up to 20 years old. This study analysed the incidence and mortality of acute and chronic myeloid and lymphoid leukaemias in Brazil from 1990 to 2021, using adjusted and estimated data from the Global Burden of Diseases Study 2021. This is an ecological time-series study with age-standardised rates, expressed per 100,000 inhabitants. Trends were assessed using Joinpoint regression, considering the average annual percentage change. The results indicated an increase in the incidence of chronic lymphocytic leukaemia (CLL) and Acute Myeloid Leukaemia in males, as well as an increase in AML-related mortality in both sexes. On the other hand, a reduction in the incidence and mortality of acute lymphocytic leukaemia (ALL) and chronic myeloid leukaemia (CML) was observed in both sexes. ALL-related mortality also decreased in females, whereas CLL-related mortality increased in males. According to age group and sex, varied trends were observed for these neoplasms. These findings highlight the need for further studies on haematologic neoplasms to inform public health policies, foster research on targeted therapies and promote advancements in the management of these diseases in Brazil.