Methylobacterium mesophilicum - is a gram-negative bacillus, most often isolated in medical establishments. For humans M. mesophilicum is considered to be conditionally pathogenic flora. Cases of infection with this agent in humans occur, as a rule, in immunodeficient individuals. A clinical description of a rare case of infection with Methylobacterium mesophilicum with development of acute meningitis in 26-year-old patient is presented in the article. A considerable decrease in bactericidal activity of neutrophils was detected in the patient. So far cases of meningitis due to Methylobacterium mesophilicum have not been described.