The effect of temperature on deet was studied at temperature ranging from 26° to 50°C in 5° increments from 30 to 50°C and 4°C increments from 26 to 30°C. A highly significant (P < 0,01) negative correlation (r = −0.9552) was found between protection times and temperatures. Five other repellents besides deet. viz. ethyl hexanediol, dimethyl phthalate (DMP), butyl 3,4-dihydro-2,2-di-methyl 4-oxo-2H-pran-6-carboxylate, and hexamethyleneimine butane sulfomide: were tested for protection time at 40°C and compared with their respective protection times at room temperature (26°C). A highly significant (P < 0,01) positive correlation was obtained (r = +0.9821) between the data at the two temperatures. Using the ratio of the protection time at 40°C to that at 26°C as an index for resistance, hexamethyleneimine butane sulfonamide withstood heat the most and ethyl hexanediol the least. Use of elevated temperature a quick method of screening insect repellents is discussed.