Medical incinerator is a technical process destroying medical waste with controlled incineration so that produce the stable ash and friendly environmental gas emition. Medical incinerator has been constructed for medical waste destroying with combustion capacity 300 kg/h. About 19 % of the input (equivalent to 57 kg) is used as fuel and produce energy 0.265 GJ. Based on design calculation was determined complete combustion process (100 % excess air) at primary chamber which energy consumption is 1.253 GJ/h need air supply that is equivalent to 13.15 Nm3/minute and 33.2 L/h kerosene. While the secondary chamber needs 0.833 GJ/h which is equal to 23.5 L/h fuel. The air is supplied using a blower having 1.00kW power; a water pump with capacity 175 watt is used for stack gas cooling. To carry the gas emitted is needed the stack, with construction the dimension is 38 em in diameter and 12 m high, producing 7.5 m/second flue gas velocity. The gas emitted of the medical incinerator has been evaluated and considered safe for atmospheric disposal and the value of the gas emition is qualified for the emition standard as required. From economical aspect calculation was determined the operational cost of the incinerator is about Rp.1.150,-/kg medical waste. Keywords: Medical incinerator, medical waste, bltnling capacity, primanj chamber, secolldanj chamber, kerosene, gas emition, environmental, retention time, operational cost incinerator. P. Sebayang, Muljadi, Deni S. Khaerudini, Anggito PT Pusat Penelitian Fisika - LIPI Kawasan PUSPIPTEKSerpong Tangerang