The objectives of this study were to explore the concurrent validity of test results of upper lifting tasks of the Ergo-Kit FCE and the Isernhagen Work Systems (IWS) FCE. Seventy-one healthy young adults performed 5 upper lifting tests with at least 5 min of rest in between. The lifting tests included 3 standard protocols and 2 modified protocols. Three criteria for concurrent validity were established: 1) Pearson correlation higher than .75, 2) nonsignificant two-tailed t test, and 3) mean difference smaller than 5 kg. The results showed that none of the criteria were met for the standard protocols. For the modified protocols criteria 2 and 3 were not met. Individual differences larger than 10 kg were found for both standard and modified protocols. It was concluded that the standard protocols for upper lifting tasks of the Ergo-Kit FCE and the IWS FCE do not meet the criteria for concurrent validity and can, therefore, not be used interchangeably.