Herbaspirillum species, colonized the plant rhizosphere, also called rhizobacteria, are plant growth-promoting bacteria. Recently we isolated Herbaspirillum from blood cultures of acute lymphoblastic leukemia (ALL) and identified by PCR and gene sequencing. Herbaspirillum may be a potential pathogenic bacteria. Although the exact role that these species play in ALL patients is unknown, their differentiation from other species has serious implications for clinical care and patient well-being.