The inactivation of radioactively labeled poliovirus type 1 and coxsackievirus B 1 in soils saturated with surface water, groundwater, and septic tank liquor was directly proportional to temperature. Virus persistence was also related to soil type and the liquid amendment in which viruses were suspended. At 37°C, no infectivity was recovered from saturated soil after 12 days; at 4°C, viruses persisted for at least 180 days. No infectivity was recovered from dried soil regardless of temperature, soil type, or liquid amendment. Additional experiments showed that evaporation of soil water was largely responsible for the decreased recovery of infectivity from drying soil. Increased rates of virus inactivation at low soil moisture levels were also demonstrated. Increasing concern over efficient use of limited water resources has resulted in research on the possible use of sewage or sewage sludges for land reclamation and fertilizer (9, 14, 18). Viruses and other pathogens remaining in the sewage or sludge could contaminate crops, surface water, or groundwater. For viral contamination to occur, however, viruses must remain infectious after a period of association with soils. Knowledge of virus persistence and movement in soils is presently incomplete and sometimes contradictory. For example, Tierney et al. (19) have shown that viruses in sewage or sludge used to irrigate crops may persist for up to 11 days in soil at summer temperatures and for over 96 days under winter conditions. Wellings et al. (23) demonstrated that enteric viruses can survive irrigation and move at least 6 m vertically and 38 m laterally through soil to monitoring wells.