Dravet syndrome (Dravet) is a severe congenital developmental genetic epilepsy caused byde novomutations in theSCN1Agene. Nonsense mutations are found in ∼20% of the patients, and the R613X mutation was identified in multiple patients. Here we characterized the epileptic and non-epileptic phenotypes of a novel preclinical Dravet mouse model harboring the R613X nonsenseScn1amutation.Scn1aWT/R613Xmice, on a mixed C57BL/6J:129S1/SvImJ background, exhibited spontaneous seizures, susceptibility to heat-induced seizures, and premature mortality, recapitulating the core epileptic phenotypes of Dravet. In addition, these mice, available as an open-access model, demonstrated increased locomotor activity in the open-field test, modeling some non-epileptic Dravet-associated phenotypes. Conversely,Scn1aWT/R613Xmice, on the pure 129S1/SvImJ background, had a normal life span and were easy to breed. HomozygousScn1aR613X/R613Xmice (pure 129S1/SvImJ background) died before P16. Our molecular analyses of hippocampal and cortical expression demonstrated that the premature stop codon induced by the R613X mutation reducedScn1amRNA and NaV1.1 protein levels to ∼50% in heterozygousScn1aWT/R613Xmice (on either genetic background), with marginal expression in homozygousScn1aR613X/R613Xmice. Together, we introduce a novel Dravet model carrying the R613XScn1anonsense mutation that can be used to study the molecular and neuronal basis of Dravet, as well as the development of new therapies associated withSCN1Anonsense mutations in Dravet.