Abstract Background: Pneumonia is the foremost cause of child death worldwide. M‐ficolin is encoded by the FCN1 gene and represents a novel link between innate and adaptive immunity. Objectives: To investigate the FCN1 −144 C/A (rs10117466) polymorphism as a potential marker for pneumonia severity and adverse outcome namely complications or mortality in the under‐five Egyptian children. Methods: This was a prospective multicenter study that included 620 children hospitalized with World Health Organization‐defined severe pneumonia and 620 matched healthy control children. Polymorphism rs10117466 of the FCN1 gene promoter was analyzed by PCR‐SSP, while serum M‐ficolin levels were assessed by ELISA. Results: The FCN1 A/A genotype and A allele at the −144 position were more frequently observed in patients compared to the control children (43.4% vs 27.6%;