Introduction: Chronic recurrent multifocal osteomyelitis (CRMO) is a very rare disease, of unknown origin that affects primarily the metaphysis of long bones.It is characterized by an insidious onset of symptoms and multiple remissions.The chronicity of symptoms, the diagnostic imaging and the lack of response to first line antibiotic treatment, should be helpful for diagnostic.Objective: Present a clinical case, based on clinical, laboratory, radiologic imaging and histopathological results, that ultimately led to the diagnostic of CRMO.Case report: 9 year old, female patient, with one month of bilateral knee and left ankle arthralgia.Bone Gammagraphy and full body MRI, showed multifocal bone inflammation.These findings led to a biopsy, that turned negative for malignancy and infection.Given all the information available from the laboratory test results, radiologic imaging and histopathological findings, CRMO diagnosis was made.NSAID treatment was order, with good results.Conclusions: CRMO is a rare disease that even to date and with cutting edge technology, still represents a diagnostic challenge that primarily relies on a high level of suspicion, for a timely and correct treatment.