Critical thermal minima (CTmin) values were determined for the Pacific white shrimp Litopenaeus vannamei juveniles at combination of four different acclimation temperatures (15, 20, 25, and 30°C) and salinity levels (10, 20, 30, and 40‰). The lowest and highest CTmin of shrimps ranged between 7.2°C at 15°C/30‰ and 11.44°C at 30°C/20‰ at cooling rate of 1°C h-1. Acclimation temperature and salinity, as well as the interaction of both parameters, had significant effects on the CTmin values of L. vannamei (P<0.01). Yet, the results showed a much more profound effect of temperature on low thermal tolerance of juveniles. Only, 40‰ salinity had an influence on the CTmin values (P<0.01). As the acclimation-temperature was lowered from 30°C to 15°C, the thermal tolerance of the shrimp significantly increased up by 3.25–4.14°C. The acclimation response ratio (ARR) of the Pacific white shrimp exposed to different combinations of salinity and temperature ranged from 0.25 to 0.27. When this species is farmed in sub-tropical regions, its pond water temperature in the over-wintering facilities (regardless of the water salinity level) must never fall below 12°C throughout the cold-season to prevent mortalities.