On the basis of two children with coexistence of atopic and seborrhoeic dermatitis, authors emphasize similarity of clinical symptoms and chronic, recurrent course of these diseases. Atopic dermatitis and seborrheic dermatitis are most common reasons of skin disorders in infants. Location and character of atopic lesions are atypical during infancy. Most often they occur on face and have erythematous-exfoliative and papulovesicular character. Pruritus and anxiety, especially in younger children are often seen. On the contrary seborrhoeic lesions are mostly seen in typical spots, including hairy head skin, where they form characteristic yellow seborrhoeic scales. Usually pruritus is not seen. Authors pay attention to heterogeneous etiopathogenesis of these diseases and underline the importance of early differentiation, which allows application of proper therapy.