Previous analyses of thermal acclimation of locomotor performance in amphibians have only examined the adult life history stage and indicate that the locomotor system is unable to undergo acclimatory changes to temperature. In this study, we examined the ability of tadpoles of the striped marsh frog (Limnodynastes peronii) to acclimate their locomotor system by exposing them to either 10 degrees C or 24 degrees C for 6 weeks and testing their burst swimming performance at 10, 24, and 34 degrees C. At the test temperature of 10 degrees C, maximum velocity (Umax) of the 10 degrees C-acclimated tadpoles was 47% greater and maximum acceleration (Amax) 53% greater than the 24 degrees C-acclimated animals. At 24 degrees C, Umax was 16% greater in the 10 degrees C-acclimation group, while there was no significant difference in Amax or the time taken to reach Umax (T-Umax). At 34 degrees C, there was no difference between the acclimation groups in either Umax or Amax, however T-Umax was 36% faster in the 24 degrees C-acclimation group. This is the first study to report an amphibian (larva or adult) possessing the capacity to compensate for cool temperatures by thermal acclimation of locomotor performance. To determine whether acclimation period affected the magnitude of the acclimatory response, we also acclimated tadpoles of L. peronii to 10 degrees C for 8 months and compared their swimming performance with tadpoles acclimated to 10 degrees C for 6 weeks. At the test temperatures of 24 degrees C and 34 degrees C, Umax and Amax were significantly slower in the tadpoles acclimated to 10 degrees C for 8 months. At 10 degrees C, T-Umax was 40% faster in the 8-month group, while there were no differences in either Umax or Amax. Although locomotor performance was enhanced at 10 degrees C by a longer acclimation period, this was at the expense of performance at higher temperatures.