BACKGROUND: In patients with coronavirus disease-19 (COVID-19), serious biomarkers (liver function tests and renal functions tests) (urea, creatinine, GOT, GPT, and LDH) are determined immediate to assess in prognosis of the severity of disease. AIM: The aim of the study was to determine correlation between biomarkers (liver function tests and renal functions tests) (urea, creatinine, GOT, GPT, and LDH) among COVID-19 patients. METHODS: A cross-sectional study, a total of 90 COVID-19 patients who attending in the Al-Hussein Medical City in Karbala, Iraq, participated in the present study within a month’s time in late December 2021 to early January of 2022. All COVID-19 patients with positive SARS-COV-2 real-time RT-PCR results were reviewed. The patients were classifying according SPO2 into three groups (mild, moderate, and severe groups). The demographic data (sex, age, and SPO2) were collected while the biomarkers (liver function tests and renal functions tests) for all patients were done by bio-base instrument (ACCENT-200 ALAT KIT). RESULTS: The white blood cell “WBC” and neutrophil in moderate and severe groups had substantially greater counts (p = 0.005) when compared with mild group while lymphocytes were considerably decreased in the severe and moderate groups (p = 0.005). In the moderate group, there was positive significant correlation among neutrophils and serum LDH (r = 0.451*, p = 0.014). There was no significant correlation between neutrophils and liver function tests. Furthermore, in the moderate patient group, a strong positively correlating notably among lymphocytes and serum LDH. Moreover, the concentration of serum GOT, GPT, and LDH (p = 0.05, p = 0.08, and p = 0.5) was higher levels in severe group when compared to moderate and mild groups, on the other hand, the renal function tests (urea and creatinine) were high serum levels in severe group than mild and moderate groups. CONCLUSION: The serum concentration of urea, creatinine, GOPT, GPT, and LDH was high in severe COVID-19 patients group, although there was no statistically significant in ALP, GPT, and urea among COVID-19 patient’s groups (mild, moderate, and severe group). The present study found no significant correlation between biomarkers (liver function tests and renal function test).