We refer a case of total knee prosthesis infected by Brucella melitensis: a 74-years-old woman, affected by knee arthritis and operated 9 years before in a different hospital with the implant of a total prosthesis to the left knee. The lapse of time between the joint implant and the onset of the general symptoms of infection was 36 months. The infection localized to the left knee 12 months later. The source was identified with the consumption of a diary unpasteurized product. The first treatment was conservative by antibiotic cocktail, then the prosthetic implant removal has become necessary. To our knowledge, in the literature only 8 cases of brucellar prosthetic infection have been previously reported (5 knee and 3 hip prosthesis): in 7 cases Brucella melitensis was isolated, in one Brucella abortus.Key words Brucellosis • Total knee arthroplasty mals (e.g. livestock breeding, veterinary medicine, butchery) and one that is related to the consumption of nonpasteurized milk and milk products [1,2]. In only 15%-20% of all cases is the diagnosis of brucellosis confirmed by culture. Most cases are diagnosed by serology with the agglutination test of Wright [3].The initial symptons of a brucellosis infection are non-specific (recurrent fever, excessive sweating, migraine headaches, apathy and asthenia). The most frequent complications affect the osteoarticular complex and can include polyarthralgia, spondylitis, sacroiliitis, coxitis, osteomyelitis and aseptic arthritis. Because brucella organisms grow intracellularly, it is necessary to use an antibiotic that not only is active against the brucella bacteria but is also able to penetrate the cell membrane. Tetracycline, rifampicin, co-trimoxazole and ami-