At the end of 2019, a new coronavirus pneumonia turned into an epidemic in China and then spread to other countries around the world. This disease was identified as the COVID-19 (SARS-CoV-2) disease. SARS-CoV-2 RNA is detected by Reverse-Transcription Polymerase Chain Reaction (RT-PCR). A positive test for SARS-CoV-2 may confirm the diagnosis of COVID-19, but the results of false negativity and false positivity can be confusing. This article describes the negative COVID-19 RNA RT-PCR test results of four cancer patients with symptoms/clinical findings suggestive of COVID-19 and also computed tomography findings consistent with viral pneumonia.