Soybean aphid, Aphis glycines Matsumura, has become an important economic pest in soybean, Glycine max L., since its introduction into the North Central United States and southern Canada. Survival and reproduction of soybean aphids exposed to constant, high temperatures (maximal lethal temperatures) has been well characterized. However, temperature effects on soybean aphid demographics under simulated field conditions are not well understood. Our objective was to evaluate the impact of fluctuating and short-term exposure to stressful temperatures on soybean aphid fecundity and survivorship on soybean under controlled conditions. Newly deposited soybean aphid nymphs (ca. 1 h old) were exposed to 16, 28, and 35ºC for 0, 4, or 12 h durations and aphid survivorship, development, and fecundity were recorded. In a second experiment, life tables were constructed for soybean aphids exposed to fluctuating temperatures ranging from 27-36ºC. Soybean aphids were exposed to fluctuating temperatures for 0, 1, 2, or 4 d with 70% RH and a 16:8 (L:D) h photoperiod. Nymphs exposed to 35ºC for 4 and 12 h and held at 28ºC recovered quickly; there were no significant differences in net fecundity or survivorship between all individuals reared at the same temperature. However, soybean aphids held at constant 35ºC never produced offspring and died within 10 d. For aphids born at 28ºC, fecundity decreased with increased exposure to fluctuating temperatures; conversely, fecundity increased for aphids born at 31ºC.