During the course of a bronchiolitis in a 3 month-old child, one blood culture yielded Brucella melitensis. The diagnosis of brucellosis is difficult in infancy because the symptoms are nonspecific and the disease may be mild and self-limited. The child received only breast milk and dietetic preparations. So, the detection in the maternal serum of a significant titer of Brucella agglutinin enabled us to consider the very rare human-to-human transmission from mother to child. Because the efficacy of ceftriaxone assessed by a favorable initial response, and in order to avoid complications due to the use of tetracyclines and cotrimoxazole in infant, our patient was successfully treated with ceftriaxone plus rifampin.