The aim of this study was to obtain an evolution of the ammonification potentials in stored urine with fecal contamination. It was found that ammonification stopped after 20 days at 30 degrees C although more than half of urea still remained. The evolution of ammonification potentials showed three simple phases: the potential increased during the first 3.5 days, after which it decreased and reached a constant state significantly more than initial phase. It was concluded that the ammonification potentials remained more than the initial value after ammonia concentration was at the stable level. Thus inhibition process rather than decline process was exhibited in stored urine with fecal contamination as shown in constant phase.