BACKGROUND: COVID-19 is a new infectious disease, for which there is currently no treatment. It is therefore necessary to explore biomarkers to determine the extent of lung lesions and disease severity. OBJECTIVE: We aimed to assess the usefulness of CRP levels in the early stage of COVID-19 and to correlate them with lung lesions and severe presentation. METHODS: Confirmed cases of COVID-19 were selected at the Fever Unit in two regions of Guizhou, China. On admission CRP levels were collected, and the diameter of the largest lung lesion was measured in the most severe lung lesion by lung CT scan. Differences in the diameter and CRP levels were compared in the following groups of patients: mild group, moderate group, severe group, and critical group. RESULT: CRP levels and the diameter of the largest lung lesion in the moderate group were higher than those in the mild group (Mann-Whitney test=-2.647, -2.171, P˂0.05), those in the severe group were higher than those in the moderate group (Mann-Whitney test=0.693, -2.177, P˂0.05), and those in the critical group were higher than those in the severe group (Mann-Whitney test=-0.068, -1.549, P˂0.05). The difference was statistically significant. CRP levels were positively correlated with the diameter of lung lesion and severe presentation (correlation coefficient=0.873, 0.734, P˂0.001). CONCLUSION: In the early stage of COVID-19 CRP levels were positively correlated with lung lesions and could reflect disease severity.