The literature review concerning selected nutritional and health aspects of applying different vegetarian diets by breastfeeding women was presented. The only two types of vegetarian diets: lactoovo- and semi-vegetarian, when properly composed, seem to be relatively safe for mother and her child. The most threatening vegetarian diets for lactating women are those including exclusively products of plant origin (so called restricted diets: vegan or macrobiotic). The results of studies performed on mothers consuming these vegetarian diets showed deficiencies in: vitamin B12 and vitamin D (in mothers and their infants) and calcium (only in lactating women). The low intake of docosahexaenoic acid (DHA) was also characteristic in this group. Additionally the endogenous metabolism of DHA is inhibited due to high proportion of linoleic vs. linolenic acid intake. It considered that lactating women on vegetarian diet should have a greater nutritional knowledge in order to avoid deficiencies which would adversely affect mother's and her child's health.