A method for producing ammonia from natural gas, fed to an autothermic reformer with an O.sub.2 rich gas. Crude synthesis gas is produced at temperatures of 900 to 1200.degree. C., pressures of 40 to 100 bar and in the presence of a cracking catalyst. The crude synthesis gas is led through a catalytic conversion system to convert CO to H.sub.2, thereby obtaining a conversion synthesis gas with a H.sub.2 content of at least 55 vol.-% and a CO content of not more than 8 vol.-%. The conversion synthesis gas is subjected to a gas purification to remove CO.sub.2, CO and CH.sub.4, thereby producing an N.sub.2--H.sub.2 mixture that is subjected to a catalytic ammonia synthesis. The ammonia produced can at least be partially converted to urea by reacting it with CO.sub.2.