Introduction: COVID-19 disease is an infectious disease characterized by a wide spectrum of clinical manifestations of varying severity. Biological markers play an important role in its management. The objective of this work is to study the association between the elevation of certain markers of inflammation: CRP, ferritin and LDH, and the severity of COVID-19. Materials and methods: This is a retrospective study carried out at the biochemistry laboratory of HMMI in Meknes, covering a series of 324 patients, hospitalized and declared positive for COVID-19. Patients are divided into 2 groups according to the severity of the disease; severe or moderate form, and all received a complete biological assessment including: CRP, ferritin and LDH. The aim of this study is to determine the role of these inflammatory markers in predicting the severity of COVID-19. Results: In a series of 324 cases, the average age is 33 years with a M/F sex ratio of 5. 40 patients developed the severe form of the disease, in whom the average age and the number of comorbidities, are both significantly higher than in the moderate forms group (age, p = 0.000; comorbidities, p < 0.05). Plasma concentrations of CRP, ferritin and LDH were respectively increased in 164 (25.3%), 128 (19.7%), and 136 (21%) patients, with a statistically significant difference between the 2 groups of patients. . However, statistical analysis shows that only CRP and ferritin levels are significant predictors of severe forms of COVID-19. A CRP level ≥ 31.80 mg/L predicts disease severity with a sensitivity of 80% and a specificity of 96.5%. For ferritin, the predictive rate of severity is ≥ 295ng/mL, with a sensitivity of 70% and a specificity of 88.7%. Discussion: Despite the limited size of our sample, the results of our study are consistent with those of the literature. They indicate that serum levels of CRP and ferritin are reliable and early predictors of the severity of COVID-19. Some studies have examined the prognostic role of other inflammatory markers, such as interleukin-6 and procalcitonin. However, it is difficult to carry out a large panel of tests in our context, given that they are not widely available. Conclusion: Our study showed that serum CRP and ferritin levels are better than LDH in predicting severe forms of COVID-19. They can be determined easily in almost all laboratories, which would help ensure adequate care and monitoring of patients upon admission.