Introduction: The aim of this study was to investigate the adherence to vaccinations, especially pneumococcal vaccinations, in lung cancer patients. Methods: the study was performed at the University Hospital Regensburg, Germany. All patients with a regular appointment scheduled between 1 December 2020 and 29 April 2021 and who provided informed consent were included. Available medical records, vaccination certificates, and a questionnaire were analyzed. Results: we included 136 lung cancer patients (NSCLC n = 113, 83.1%, SCLC n = 23, 16.9%). A correct pneumococcal vaccination according to national recommendations was performed in 9.4% (12/127) of the patients. A correct vaccination was performed for tetanus in 50.4% (66/131), diphtheria in 34.4% (44/128), poliomyelitis in 25.8% (33/128), tick-borne encephalitis in 40.7% (24/59), hepatitis A in 45.5% (7/11), hepatitis B in 38.5% (5/13), shingles in 3.0% (3/101), measles in 50.0% (3/6), pertussis in 47.7% (62/130), influenza in 54.4% (74/136), and meningococcal meningitis in 0% (0/2) of the patients. Conclusion: adherence to pneumococcal vaccinations, as well as to other vaccinations, is low in lung cancer patients.