Morganella morganii (M. morganii) is a Gram-negative aerobic and facultative anaerobic rod, belonging to the Enterobacteriaceae family. This pathogen is uncommon in community-acquired infections, most often being found in postoperative nosocomial and urinary tract infections. Infection of the central nervous system with this pathogen is rare. We present the case of a 66-year-old patient who underwent colon cancer surgery, chemotherapy and radiotherapy, had left iliac anus, type 2 diabetes and developed acute meningoencephalitis caused by M. morganii. Cerebrospinal fluid examination revealed increased number of polymorphonuclear neutrophils, modified biochemistry and AmpC beta-lactamase producing M. morganii strain. After initiation of antibiotic treatment, initially with empirical therapy represented by meropenem and vancomycin, afterwards adjusted to meropenem and ciprofloxacin, according to the stain’s susceptibility to antimicrobials the patient’s evolution was favourable, in spite of the existence of two immune suppressing conditions.