The first two articles of this series dealt with errors in neonatology, which occurred during the ‘‘Hands Off’’ years (1920 to 1950) and the ‘‘Heroic’’ years (1950 to 1970). From 1970 on, we call the ‘‘Experienced’’ years. This period is characterized by a refinement of the methods and treatments introduced in the earlier periods. The algorithms of neonatal intensive care become similar around the world. Some new treatments are studied before being generally accepted. Randomized controlled trials are more common. Organizations such as the FDA and committees of the American Academy of Pediatrics are more involved in assessing problems and making recommendations. Institutional research review boards become more authoritative, and there seem to be fewer errors. Perhaps we have learned from these past experiences. However, that may not be true. The increased complexity of our care and of our patients may simply make errors less apparent. In this article, we will discuss problems with infant formulas, ‘‘inactive’’ ingredients in drugs, erythromycin, steroids and conclude with an analysis of the causes of errors and ways to avoid errors in the future.