The relationship between working memory, intelligence and problem-solving is explored. Wittmann and Suss [Wittmann, W.W., & Suss, H.M. (1999). Investigating the paths between working memory, intelligence, knowledge, and complex problem-solving performances via Brunswik symmetry. In P.L. Ackerman, R.D. Roberts (Ed.), "Learning and individual differences. Process, trait content determinants" (pp. 77-104). Washington: APA.] showed that working memory shares unique variance with problem-solving beyond intelligence. We used measures of visuo-spatial intelligence (G[subscript v]) and working memory to predict performance in the simulation-based problem-solving test "MultiFlux" in a sample of N = 144 undergraduate students. SEM analyses showed that while there was no unique contribution of G[subscript v'], working memory was a significant predictor of "MultiFlux" rule knowledge and rule application. This result is not in line with findings by Wittmann and Suss. It is discussed that task content (verbal, figural, numerical) might play an important role in explaining the relationship between intelligence and problem-solving. (Contains 3 tables and 3 figures.)