In the past decades there has been an increased interest in hypoxic manipulation (HM) (i.e. altitude training, live high + train low (LH+TL) etc.) for improvement in sea-level performance. The efficacy and mechanism of HM has been conflicting. A method of resolving the equivocal nature of HM data is through the use of meta-analysis. PURPOSE: The purpose of this meta-analysis was to identify the effects of HM versus normoxic training on VO2max and sea-level performance. METHODS: An online database and the reference lists of peer-reviewed journal articles were used to find pertinent journal articles. A total of 74 journal articles were found, of which 32 met the inclusion criteria and 16 of the 32 were reviewed for this preliminary study. The journal articles included in the meta-analysis had to meet the following 1) used a control group in their design and 2) reported means and standard deviations with their results. The dependent variables were VO2max and exercise performance. Exercise performance was defined as time trial performance, peak power during a GXT, or total work capacity. The independent variable was HM and included traditional altitude training, LH+TL, live low + train high and intermittent hypoxic exposure. There were a total of 43 extracted data points: VO2max (n = 19 control and n = 24 HM) and performance (n = 20 control and n = 23 HM). Effect size (ES) was calculated using Cohen's d: ES= (posttest mean-pretest mean)/pretest SD. A t-test was used to determine the difference between the mean ES for the control and the HM. RESULTS: The mean ES for control and HM were.28 and.33 for VO2max and.29 and.50 for performance, respectively. There were no difference in ES for VO2max but a statistically higher ES was observed for performance in HM group. CONCLUSION: In summary our data indicates a statistically higher ES for performance in HM versus normoxic training but no differences were observed between ES's of VO2max.