Due to lack of families suitable for linkage analysis and positional cloning most of the genetic causes of human dilated cardiomyopathy (DCM) are still unknown. To facilitate rapid identification and validation of novel DCM disease genes appropriate animal models are needed. To assess here for the first time whether the zebrafish is a suitable model organism to validate DCM candidate genes using antisense knock-down strategies, we inactivated in zebrafish known human DCM disease genes and then evaluated the resulting cardiac phenotypes. Consistently, knock-down of the here selected human DCM genes leads to severe heart failure with impairment of systolic cardiac function in zebrafish. Furthermore, gene-specific differences which are also seen in human DCM can be reliably reproduced in the zebrafish model. Our results indicate that the zebrafish is a suitable model organism to rapidly evaluate novel DCM disease genes in-vivo.