Exclusive breastfeeding in the early infancy, continued partial breastfeeding and timely transition to the only selected foods are reported in nonhuman primate infants. In humans there is growing body of evidence about short- and long-term consequences of feeding practices in the first years of life. Young child must be fed and decisions must be made about how this should be done. Cow’s milk and milk-derived products constitute a significant part of the Polish diet. The feeding of cow’s milk to infants has undesirable consequences in several areas, like iron deficiency, food allergy, high renal solute load and the risk of severe dehydration, autoimmunity, obesity, and displacement of breast-milk or formula consumption. Faced with a parent asking at what age the whole cow’s milk and milk products can be introduced to the diet, the GP or paediatrician has to integrate a reasonable schedule based on pathophysiological and epidemiological data mixed with evidence-based consensuses and expert guidelines. In this article a review of the evidence and guidelines data for the timing of the introduction of whole cow’s milk and use of skimmed milk is presented. Professionals who make decisions regarding feeding of infants and young children have to consider multiple variables. Further studies are now warranted to examine a broader range of feeding patterns to obtain the empirical information that will be needed to establish appropriate cow’s milk feeding recommendations and also to ensure decreased risk of allergy and iron deficiency development, as well as minimum displacement of breast-milk consumption. Conclusions: 1) When whole cow’s milk is introduced a sufficient iron intake should be secured. Experts from Poland and most other countries recommended introduction of cow’s milk not before the age of 12 months. 2) Cow’s milk with a reduced fat content may be an acceptable alternative for children between 12 months and 3 years with clearly recognised indications. 3) A huge intake of cow’s milk (in so called milkaholics) disturbs diversification of the diet.