This review summarizes the evidence on antiphospholipid (aPL) antibodies and related thromboembolic events in patients with solid tumors. Data sources included Medline, EMBASE, Web of Science, PubMed ePubs, and the Cochrane Central Register of Controlled Trials through August 2019 without restrictions. Observational studies that evaluated patients with solid tumors for the presence of aPL antibodies were included. Data were extracted and quality was assessed by one reviewer and cross-checked by another. Thirty-three studies were identified. Gastrointestinal (GI) and genitourinary (GU) cancers were the most frequently reported. Compared with healthy patients, patients with GI cancer were more likely to develop anticardiolipin antibodies (risk ratio [RR], 5.1; 95% confidence interval [CI], 2.6-9.95), as were those with GU (RR, 7.3; 95% CI, 3.3-16.2) and lung cancer (RR, 5.2; 95% CI, 1.3-20.6). The increased risk for anti-β2-glycoprotein I or lupus anticoagulant was not statistically significant. Patients with lung cancer who had positive aPL antibodies had higher risk of developing thromboembolic events than those who had negative antibodies (RR, 3.8%; 95% CI, 1.2-12.2), while the increased risk in patients with GU cancer was not statistically significant. Deaths due to thromboembolic events were more common among patients with lung cancer who had elevated aPL antibodies. A limitation of this review is that the results are contingent on the reported information. We found an increased risk of developing aPL antibodies in patients with GI, GU, and lung cancers resulting in thromboembolic events and death. Further studies are needed to better understand the pathogenesis and development of aPL antibodies in cancer.© 2020 by The American Society of Hematology.