Previous reports have described complications resulting from inadvertent intravenous administration of breast milk: hyperosmolarity, microembolism, hypersensitivity and septicaemia. We present the case of a premature infant who was accidentally given expressed breast milk (EBM) intravenously. The non-fatal outcome of the patient in the first month of the incident may have been related to pulmonary embolism and supportive treatment, which was started from the first instance of the milk administration. The fatal outcome of the patient was related to severe septicaemia in the second month of the administration. Particular care must be taken in the case of the patient who is receiving synchronous enteral and intravenous infusion therapy. Caregivers as well as healthcare professionals should be enlightened on the importance of this subject matter.