A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was whether patients with haematological malignancy (HM) who need cardiopulmonary bypass (CPB) have a higher short-term mortality or a higher chance of disease progression secondary to CPB. Altogether, 107 papers were found using the reported search terms, but ultimately only eight were relevant to our subject. We found four case series and four case–control series. Most of the found papers were only short series. The largest series included 56 patients with HM and requiring CPB, suggesting that HM patients rarely require CPB surgery and/or are not operated on. Most of these studies showed that the overall postoperative morbidity rate was increased, reaching 50–60% of the patients. These comorbidities were mainly related to postoperative infections, bleeding and blood transfusions, which were highly significant. However, in most papers, the postoperative hospital stay was not different and the in-hospital mortality rate of HM patients was similar to that of healthy patients. One paper demonstrated that the time taken before initiating chemotherapy was longer in patients who underwent CPB surgery. No paper reported an acute change in blood disorders. Long-term mortality rates were not mentioned in some papers, but when it was stated, the HM patients’ long-term mortality seemed not increased by using CPB surgery, with more than 80% survival at 3 years and 20–25% progression of the disease at 3 years. Although these study limitations are linked to the low-evidence levels in some of the papers used, haematological malignancies should not be considered a contraindication for cardiac CPB surgery.