This report describes the case of a 45-year-old woman with a 5-month history of fever, generalized malaise, myalgia, lower back pain and difficulty in walking. Serodiagnosis for brucella, carried out at the onset of symptoms 5 months previously, was negative. When the patient was admitted to our hospital there was contracture of the paraspinal muscles but no peripheral nerve damage. Laboratory tests showed positive agglutination for Brucella and an increase in the rate of dilution from 1/160 to 1/640 over 2 weeks. Radiographs and a computed tomography scan of the spine revealed bone erosion in the posterior borders of the L4-L5 vertebral end plates and a soft tissue mass surrounding the interposed disc and protruding into the spinal canal. Magnetic resonance imaging confirmed the presence of a paraspinal abscess around the affected disc and tissue edema. Culture tests of the blood and abscess tissue, taken by biopsy, were negative. Rifampicin treatment (600 mg daily), combined with a bust cast to immobilize the spine, led to clinical healing without the need for surgery. Because onset symptoms are nonspecific and insidious, in nonrisk subjects a diagnosis of brucellosis may sometimes be suspected only if there are local symptoms. The phenomenon of the absence of positivity in patients with a high antibody titer should also be considered Cases such as that described herein demonstrate the need for culture tests and serodiagnosis, even in nonrisk patients with persistent fever and arthralgia, to prevent the later complications of brucellosis.