Although vaccination is efficacious and prevents infection in the general population, there is limited data about Coronavirus disease-19 (Covid-19) occurrence after vaccination in cancer patients. It was aimed to evaluate the efficacy of BNT162b2 (Pfizer-BioNTech) and CoronaVac vaccines against Covid-19 in patients with cancer. In this single-center, retrospective, cross-sectional, and descriptive study, the data of cancer patients referred to the medical oncology clinic of a university hospital were analyzed. The sample of the study consisted of cancer patients who had Covid-19 or were vaccinated against Covid-19. A total number of 2578 patients were included in the study. Of the patients, 2000 have never been infected with severe acute respiratory syndrome coronavirus and 578 patients have had a positive reversetranscription polymerase chain reaction (RT-PCR) for Covid-19. It was found that 2094 patients (81.2%) were fully vaccinated, and 484 patients (18.