Drinking water is obtained in Kuwait by blending desalinated seawater with 5–10% brackish water. Chemical analysis of trihalomethanes (THMs) was performed on 624 water samples collected from private residences and government buildings from December 2003 to May 2005. The highest value recorded (91.01 μg/L), exceeds the maximum contaminant level (MCL) set by the U.S. EPA. Significant variations in the levels of total THMs (TTHMs) either between various sampling locations or between indoor and outdoor sampling points were found. TTHM levels were mostly higher in the outdoor samples. The maximum recorded value of TTHMs in the indoor drinking water has significantly increased from 50.5 μg/L in 1988 (average 25.6±9.1μg/L) to 90.5 μg/L (average 45.5±2.6μg/L) in this study. Brominated THMs are the dominant species, and bromoform is the most dominant one. TTHMs values are found mostly higher in winter, in contrast to other studies on drinking water of freshwater sources.