Atopic diseases are a major public health problem worldwide, and several factors are thought to contribute to this rapid increase. The observed association between mode of delivery and risk of atopy in childhood has had a great deal of interest during the past few decades. In fact, even during delivery, exposure to antigens can index immune system in newborn, which induces the release of biologically active molecules, which are polarizing immune responses toward the T-helper 2 atopic profile. However, to date, studies on the relationship between mode of delivery and atopy have produced conflicting findings. The aim of this review was to summarize what is known about the relationship between mode of delivery and risk of atopic diseases in children. A literature search of electronic databases was undertaken for the major studies published from 1994 to today. The databases searched were PubMed, EMBASE, Medline, and Cochrane Library. The following key words were used: mode of delivery, cesarean section, vaginal delivery, atopy, and atopic diseases.