1. Relationship between the water content of dormant seeds of genus Mentha and their sensitivity to γ-rays (60Co) was studied. 2. Sensitivity of dormant seeds to radiations was at a minimum when they contained from about 11 to 20% water, except for M. arvensis L. (40KR) seeds. 3. Resistance of dormant M. arvensis (40KR) seeds to T-rays was at a maximum when they contained from 8 to 20% water. 4. In general, sensitivity of dormant seeds of genus Mentha to radiation is increased by either a low or a high water content.