Creatine supplementation has been reported to improve certain aspects of cognitive and psychomotor function in older individuals and in young subjects following 24 and 36 h of sleep deprivation. However, the effects of creatine supplementation on cognitive processing and psychomotor performance in non-sleep deprived young adults have not been assessed with a comprehensive battery of neurocognitive tests. The primary objective of this study was to examine the effects of creatine supplementation on cognitive processing and psychomotor performance in young adults. Twenty-two subjects (21+/-2 yr) ingested creatine (0.03 g/kg/day) or placebo for 6 weeks in a double-blind placebo-controlled fashion. Subjects completed a battery of neurocognitive tests pre- and post-supplementation, including: simple reaction time (RT), code substitution (CS), code substitution delayed (CSD), logical reasoning symbolic (LRS), mathematical processing (MP), running memory (RM), and Sternberg memory recall (MR). There were no significant effects of group, no significant effects of time, and no significant group by time interactions for RT, CS, CSD, LRS, MP, RM, and MR (all p>0.05), indicating that there were no differences between creatine and placebo supplemented groups at any time. These results suggest that six weeks of creatine supplementation (0.03/g/kg/day) does not improve cognitive processing in non-sleep deprived young adults. Potentially, creatine supplementation only improves cognitive processing and psychomotor performance in individuals who have impaired cognitive processing abilities.