The paper brings data about heat balance of the killed steel ingot head. The balance is obtained on basis of the temperature measurement in the system: ingot body - ingot head - ingot mould - insulating sleeves – radiation shield - ambient. The measurements were performed using model sys-tem (1:5) of the 20000 kg flat ingot. The balance shows that about 86% of the heat issued during solidification of the ingot head is transferred to the ingot mould through the insulating sleeves. In order to decrease this heat, insulating sleeves of low thermal conductivity are required, which should allow reducing dimensions of the ingot head and increasing the metal yield.