Whenever an anesthetic is needed during the breast feeding period, potential pharmacological side-effects imposed on the infant by any kind of anesthetic agent used during both general and regional anesthesia are in contrast to the potential beneficial effects of breast feeding for the infant and the mother. Despite an increasing knowledge and understanding of the mechanisms of excretion of drugs and their metabolites through breast milk, information about most anesthetic drugs are still either inconclusive or contradictory. Often it is impossible to decide whether a certain substance that is potentially excreted through breast milk might be harmless or harmful for the breast-fed infant. In addition to that only few anesthetic agents and drugs used in conjunction with an anesthetic are officially approved for use during pregnancy and the period of breast feeding and for medico-legal reasons pharmaceutical companies generally advise against the use of any of those drugs during this period. However, based on the knowledge of pharmacological properties of commonly used anesthetic agents it is reasonable to assume that continuing breast feeding in the immediate postoperative period after a single anesthetic can be considered safe for the infant since no adverse effects caused by or secondary to the single use of those drugs can be expected. Provided there is a careful choice of anesthetic drugs, there is no need to consider that a single general or regional anesthetic is an indication to stop breast feeding. Even planned elective surgical procedures do not need to be postponed. No scientifically based interval between surgery under general or regional anesthesia and resumption of breast feeding can be recommended. Instead current opinion is that breast feeding can be resumed as soon as the mother feels physically and mentally capable to do so.