Chikungunya virus (CHIKV) has never been detected in human breast milk. This is a brief report of CHIKV infection in a breastfeeding woman of a 3-month-old baby. The mother’s CHIKV-RT PCR was positive in serum, urine and milk. The baby’s CHIKV serology and reverse transcription polimerase chain reaction (RT-PCR) were negative. The detection of CHIKV in milk raises clinical and epidemiologic questions.