Coronavirus disease 2019 (COVID-19) is known to be affected by underlying diseases of the respiratory system. In this meta-analysis, the keywords of COVID-19, underlying diseases, symptoms, and mortality were searched in national and international databases to obtain the related studies. The inclusion criteria were as follows: interventional, clinical, descriptive and cross-sectional, and studies focusing on COVID-19. This study was conducted based on Preferred Reporting Items for Systematic Reviews and Meta- Analyses protocol. Eighteen studies were selected to be finally analyzed. The mean percentage of mortality was 14% (I2 ¼ 98.9, P<0.001). The most common symptoms were fever (91%, I2¼88.5, P<0.001) and cough (71%, I2¼84.5, P<0.001), and the most frequent underlying diseases were hypertension (41%, I2¼98.9, P<0.001), diabetes mellitus (18%, I2¼88.7, P<0.001) and cardiovascular disease (11%, I2¼87.7, P<0.001). Findings of present study suggest that individuals with underlying diseases have a higher rate of mortality following COVID-19 infection.