A rapid determination of Ammonia in urine has been achieved. Gaseous ammonia is evolved by alkylifying urine with a saturated solution of K2CO3at 80°C followed by separation of the gas phase and measurement of characteristic absorption at 197.2 nm. The linear range of the method is between 0 and 200 μg NH3/ml. The recovery of ammonia from spiked urine samples is 106.5%. Typical results obtained on five samples from healthy subjects are presented and good agreement with a reference method is shown. Automation has been achieved by the use of a mechanical sampler, a heating bath and a peristaltic pump.