The novel coronavirus disease 2019 (COVID-19) has turned into a global public health emergency after the first patients were detected in Wuhan, China, in December 2019. Methods This case-control study was conducted in two hospitals of Alborz Province in Iran. All symptomatic adults hospitalized as COVID-19 patients with compatible CT scan findings and available RT-PCR results were recruited in this study. The patients were categorized in positive and negative RT-PCR groups and evaluated for symptoms, initial vital signs, comorbidity, clinical and laboratory findings and the results were assessed by SPSS software. Results Between March 5 to April 5, 2020, 164 symptomatic COVID-19 patients were studied. In total, there were 111 RT-PCR positive (67.6%) and 53 RT-PCR negative patients (32.4%). In terms of statistics, the frequency of symptoms revealed no difference, except for cough (P.V:0.008), dizziness (P.V: 0.048) and weakness (P.V:0.022). Among initial vital signs, PR (P.V:0.041) and O2 Saturation (P.V: 0.014) were statistically different between the two groups. Evaluation of comorbidities revealed no difference except for hyperlipidemia (P.V:0.024). In comparison of laboratory findings, only WBC count (P.V: 0.001), lymphocyte count (P.V: 0.001) and Hb (P.V:0.008) were statistically different between the two groups. Conclusion In case of negative RT-PCR result, it is necessary to take a logical approach, and we recommended that the physician decide according to clinical manifestations, laboratory findings, and positive CT result