show Abstracthide AbstractINTRODUCTION: Leg ulcer is a common complication of Sickle Cell Disease (SCD), which is painful and difficult to treat, due to its extended healing process. The microbiota compositional structure of these wounds is still poorly known. OBJECTIVE: To investigate the diversity and core of the microbiota in leg ulcers and intact skin of SCD patients and intact skin of controls. METHODS: This is a cross-sectional study that included leg ulcer samples (G1), adjacent intact skin to the ulcer (G2), intact skin from patients with SCD without ulcer (G3) and intact skin from healthy controls (G4). Microbiota was characterized by sequencing the 16S rRNA gene. RESULTS: A total of 84 samples were sequenced. Leg ulcers samples had lower alpha and beta microbial diversity as compared to intact skin. The genus Staphylococcus significantly predominated in the leg ulcers (p=0.002); while Ralstonia predominated in intact skin (p= 0.042) when samples from the same patient (G1 versus G2) were compared. Intact skin from SCD patients (G2 and G3) significantly differ from healthy controls (G4) when beta diversity was analyzed by different indexes. Ralstonia was the only genera showing a significant difference (p=0.023), with a median percentage of 11.03 (G2), 13.60(G3) and 5.61(G4). CONCLUSION: Microbial diversity is lower in SCD leg ulcer samples. Intact skin from SCD patients have a different beta diversity as compared to healthy controls. Staphylococcus predominanted in leg ulcers. More studies are needed to understand if Ralstonia has a role in the development of leg ulcers in SCD patients.