This was multicenter study of the district of Sylhet of Bangladesh to evaluate the clinical features and coexisting diseases of COVID-19 patients. The secondary objective was to compare the clinical features and coexisting diseases in different age groups and among severe and non-severe participants. This was a cross-sectional study. Study places were COVID-19 isolation units of four tertiary hospitals of Sylhet district of Bangladesh. Total number of participants was 481. Total 272 participants out of 481 were tested COVID-19 positive. Mean age was 60.72 years for the COVID-19 patients. Fever (p=0.008) and Diarrhea (p=0.0184) were higher in the COVID-19 positive group. Among the 272 positive patients HTN (p<0.001), DM (p<0.001), Chronic kidney disease (CKD) (p<0.001) and ischemic heart disease (IHD) (p<0.001) were significantly more in number in the older age group (60 years and older). Mortality was also higher (p=0.00078) in the older age group. Regarding the clinical feature shortness of breathing (SOB) was higher in number (p=.009) in the severely ill patients. COPD / asthma was significantly higher (p=.0011) in the severely ill group. Older group COVID-19 patients are at risk of higher mortality. Respiratory supports like high flow nasal cannula (HFNC), non-invasive and mechanical ventilators requirement were significantly higher in the older group.