Beta-coronavirus, which caused Severe Acute Respiratory Coronavirus-2 Syndrome (SARS-CoV-2), a major respiratory outbreak in Wuhan, China in December 2019, is now prevalent in many countries around the world. Identifying PCR-based viruses is a well-known and relatively stable protocol. So diagnosis is very important for early identification of disease and to prevent further spread. In this study, we evaluated the power of a conventional RT-PCR to detect SARS-CoV-2 by two different genes. Material and Methods: We did comparative analysis for RNA dependent RNA Polymerase (Rdrp gene) and Spike (S gene by) RTPCR. We took Two hundered Seventy four (274) Nasopharangeal samples came from different hospitals of Najran zone and run samples in three runs in three different runs and we did comparative analysis of Rdrp gene using Ko gene kit and S gene using Altona kit. Results: Analysis was done Qualitatively. We compared Rdrp gene with S gene. We find Sensitivity-100 % and Specificity-96%.In Second run Sensitivity was 100%, Specificity was 98%. In third run Sensitivity and Specificity was 100%.So by comparative analysis of Rdrp and S gene showed that diagnosis by Rdrp gene is more sensitive and specific than S gene. Conclusion: Detection of Rdrp gene for SARS CoV2 is more sensitive and specific than Sgene.But diagnosis by Symptoms, Serology, Chest X-Ray and Chest CT Scan gives additional help.