Oral administration of 20-30 g creatine monohydrate per day for 5 days has been shown to increase the Cr and phosphocreatine (PCr) contents of the quadriceps femoris muscle in man (Harris et al. 1992) and to delay the development of fatigue during repeated bouts of maximal exercise (Greenhaff et al. 1992).  The biochemical findings have implications to ATP resynthesis during exercise and to H⁺ buffering.  In this study the effect of Cr ingestion on the running ability of university level athletes was tested. Ten trained middle distance runners at Tartu University (mean age 24 [S.D. 3.0]; weight 71.6 [S.D. 5.02] kg; height 183 [S.D. 2.1] cm) were divided equally into test (T) and placebo (P) groups.  T subjects consumed 6 x (5g Cr·H₂O + 5 g glucose) per day and P subjects 6 x 10 g glucose per day, for 6 days.  Prior to and following Cr supplementation, subjects performed (on separate days) 4 x 300 m and 4 x 1000 m runs with 4 and 3 minute rest intervals, respectively, between repetitions.  Subjects aimed to run at a velocity of 90-95% of their best, throughout.  Subjects were first familiarized with the experimental procedures to be used and their informed consent obtained. Results indicated an improvement in running times with Cr supplementation.  The reduction in running time over the final 300 m and 1000 m runs was significantly greater in T compared to P subjects, as was also the reduction in the 4 x 1000 m  running time.  Best 300 m and 1000 m times decreased significiantly by -0.3 (S.D. 0.09) seconds and -2.1 (S.D. 0.62) seconds with Cr supplementation but were unchanged with the P Group.