WHO recommends exclusivebreastfeeding until 6 months and thereafterstepwise introduction of complementaryfoods (CF). In developing countries, theglobal DHS survey indicates that infantcohorts who are not exclusively breastfeduntil 6 months (i.e. introduction of CF<6 months) have a higher prevalence ofstunting and wasting and suffer from moreinfections. Infants who continue to bebreastfed between 6 and 12 months andreceive CF have less infactions than infantswho are no more breastfed. ESPGHANandAAP committees repeatedly providedcomments on time of introductionof CF in developed countries.Theirrecommendations are based on studieswhich focus on health benefits/-risks inrelation to time of introduction of CF:Obesity. Two systematic reviews in thepast did not indicate a strong associationbetween time of introduction of CF andchildhood obesity in breast- and formulafedinfants. However, two recent big cohortstudies in preschool children show strong astrong association between BMI at 3-4 yearsand introduction of CF <4 months.Allergy. Based on the studies available,EACCI 2014 concluded that there is no needto avoid introducing complementary foods(cow´s milk, egg, fish, nuts etc.) beyond 4months, and currently, the evidence doesnot justify recommendations about eitherwithholding or encouraging exposure topotentially allergenic foods after 4 monthsonce weaning has commenced, irrespectiveof atopic heredity.Gluten. The prevent CD trial (7 Europeancountries) found that in high-risk childrenfor celiac disease breastfeeding duration ortime when gluten was introduced has nopreventive effect. Delayed introduction ofgluten does not protect from celiac diseasebut delays the onset of disease.Iron deficiency. Feeding iron-fortifiedcomplementary foods and meat reduces therisk of iron-deficiency anemia by 50 percent.Conclusion. In most developed countries,CF in infants are introduced between 4 and6 months. There is now sufficient scientificevidence that starting CF during this timewindow is adequate and safe.