Background: In developing countries, the inclusion assessment of the undernourished child in hospital is limited to simple routine examinations as in any pathology. The objective of the present study is to evaluate the relevance of the biological parameters routinely requested in addition to the parameters of undernutrition per se. Material and methods: Descriptive and analytical study carried out in Brazzaville among hospitalized and malnourished children from one to 59 months. Eight biological parameters were measured: C-reactive protein, orosomucoid, albumin and transthyretin using Cobas c311; blood count using Sysmex XN350 counter, serum protein electrophoresis on HELENA chain, sedimentation rate, and HIV retroviral serology. The R software was used for statistical analysis and the significance threshold was set at 0.05. Results: The blood count of the malnourished child reported a hypochromic microcytic anemia associated with hemodilution. The SV was moderately accelerated in a non-significant manner. Inflammatory proteins were statistically higher in severe undernutrition (p˂0.001). Serum albumin disturbances were significantly lowered in acute undernutrition (AD, p˂0.001), and not significantly in chronic undernutrition (CD). Transthyretin was significantly lowered in both forms of undernutrition (p˂0.05). Regarding serum protein electrophoresis, only albumin was significantly lowered (p˂0.001), the other fractions being normal. There was no association between undernutrition and HIV. Conclusion: The dosage of nutritional and inflammatory proteins should be promoted in our health centers for the management of undernutrition. Key words: C-Reactive Protein, Orosomucoid, Albumin, Transthyretin, undernutrition.