Energy saving as a result of make up gas (MUG) drying on mol. sieves commissioned in 3 NH3 plants was estd. Even in case of the NH3 syn-loop licensed by H. Topsoe, significant energy savings resulted from MUG drying amounting to 0.3-0.6 GJ/t NH3 were achieved. The MUG drying unit implemented in the KBR 1000 tpd NH3 plant resulted in decrease of energy consumption by 0.74 GJ/t NH3, and even by 1.15 GJ/t when estd. together with extra benefits from increased capacity of the plant from 1200 to 1400 tpd.