The author presents the possible pathomechanism of brain damage in NKH and the clinical course of severe - newborn and infants - atypical type of the disease. Characteristic for the newborn type EEG patterns has been discussed. Among the detailed presentation of diagnostic methods it was stressed that besides high concentration of glycine in blood and urine, the necessary parameters are high glycine ratio of cerebro-spinal fluid to blood serum, and the detailed differentiation with many transient and persistent hyperglycinemic states, the most important of them being organic acidurias which need the estimation of urinary organic acids. Possibilities of prenatal diagnostic and molecular identification are presented. All the treatment methods used up to now have been presented with special attention to natrium benzoate and dextrametorphan being used together.