Two cases of mothers given postpartum short-term administration of amiodarone, with and without bisoprolol, are described along with determinations of amiodarone and (±)-bisoprolol in the breast milk. In one mother given a cumulative total of amiodarone of 8 g over 1 week, concentrations 11 days after the drug had been stopped were initially deemed sufficient to pose a risk to an infant. Over the next 5 days the concentrations steadily dropped with amiodarone and desethylamiodarone concentrations being found to be at a level comprising minimal risk to the infant. Bisoprolol was not found in the expressed breast milk. In the second case the mother was given a single 150 mg dose of amiodarone and breast milk concentrations were measured on postpartum days 4 and 5. Breast milk amiodarone concentrations were very low and of little concern clinically had the mother breast fed her baby. The risk to the baby of ingesting breast milk after amiodarone administration postpartum depends on the duration of amiodarone exposure, with a single dose posing minimal risk. Bisoprolol does not appear to accumulate to any great extent in breast milk.