Stability of nitrogen compounds in the water-extract of ginseng has been investigated in terms of concentration and SDS-PAGE protein pattern as functions of times and temperature. The concentration of free amino-nitrogen in the extract of fresh ginseng varied with time at various temperatures. Especially at temperature over 90$^{circ}C$, it showed a tendency of steady declease at a considerably fast rate. In the case of red ginseng which had been commercially processed and stocked for 1-7 years, it was found that the free amino-N concentration diminished gradually depending on the length of stock period of samples. This result may be comparative to another observation that the amount and density distribution of precipitate from extract varied with the lapse of stock time, based on accelerated sedimentation test. The number of SDS-PAGE protein bands was observed to be at least seven when determined with the extract of fresh ginseng. However, it tended to reduce finally to be one band when the extract was kept at a rather high temperature for a long time.