ABS TRACT Cancer patients are one of the susceptible populations at risk of infections due to intensive and immune response-altering treatments. Among the infections, Streptococcus pneumoniae-related infections have a significant impact on cancer patients. These infections can be seen as mild or invasive type which varies in severity according to the type of cancer. Invasive pneumococcal disease is a serious infection that increases morbidity and mortality in cancer patients. Ensuring the integrity of patients' immunity is essential in order to maintain safe and effective cancer treatment processes. International guidelines and health authorities recommend that cancer patients should receive pneumococcal vaccines against pneumococcal diseases. The administration of vaccines in cancer patients is more complicated than in any other patient groups due to ongoing immunosuppressive treatments, which results in not achieved desired rates in pneumococcal vaccination. The vaccination process requires comprehensive assessment of the factors directly related with cancer, such as cancer type/diagnosis, cancer stage, type of treatment and scheduled treatment along with other patient-related factors. Sustainability of immunization in adult population can be achieved by implementation of vaccination programs, although logistics, economic, social, and epidemiological factors hinder its implementation. In order to increase the vaccination rates, health professionals should work in cooperation with the patient. Pharmacists, as healthcare professionals, have contributed to increased vaccination rates in cancer patients by providing vaccine consultancy and as vaccine practitioners in some countries. This review focuses on pneumococcal infections observed in cancer patients, vaccination process, and pharmacist's role in vaccination.