INon-glycosylated stimulating factor of granulocyte colonies (G-CSF) which is obtained by recombinant technology. It is practically identical to the naturally occurring product that is found in the breast milk.It is indicated for the treatment of cancer-related neutropenia, and autologous bone marrow transplantation. At last update no published data on excretion in breast milk were found. A high molecular weight makes unlikely its excretion into breastmilk in a significant amount.Its low oral bioavailability hampers absorption into infant plasma from the breast milk ingested, as for their proteic nature it is degraded in the gastrointestinal tract, not being absorbed. Other substances similar in composition and action as Filgrastim and Lenograstim are excreted into breast milk in trace amounts and have been used to treat sepsis and necrotizing enterocolitis in newborn and premature without harmful effects in the infants. Until more data about this drug regarding breastfeeding is obtained, alternatives that are known to be safer should be preferable, especially during the neonatal period and/or in case of prematurity.