The CRISPR/Cas9 system allows scarless, marker-free genome editing. Current CRISPR/Cas9 systems for the fission yeast Schizosaccharomyces pomberely on tedious and time-consuming cloning procedures to introduce a specific sgRNA target sequence into a Cas9-expressing plasmid. In addition, Cas9 endonuclease has been reported to be toxic to fission yeast when constitutively overexpressed from the strong adh1promoter. To overcome these problems we have developed an improved system, SpEDIT, thatuses a synthesised Cas9 sequencecodon-optimised for S. pombeexpressed from the medium strength adh15promoter.The SpEDITsystem exhibits a flexible modular design where the sgRNA is fused to the 3' end of the self-cleaving hepatitis delta virus (HDV) ribozyme, allowing expression of the sgRNA cassette to be driven by RNA polymerase III from a tRNA gene sequence.Lastly, the inclusion of sites for the BsaI type IIS restriction enzyme flanking a GFP placeholder enables one-step Golden Gate mediated replacement of GFP with synthesized sgRNAs for expression. The SpEDITsystem allowed a 100% mutagenesis efficiency to be achieved when generating targeted pointmutants in the ade6 + or ura4 +genes by transformation of cells from asynchronous cultures. SpEDITalso permitted insertion, tagging and deletion events to be obtained with minimal effort. Simultaneous editing of two independent non-homologous loci was also readily achieved. Importantly the SpEDITsystem displayed reduced toxicity compared to currently available S. pombeediting systems. Thus, SpEDITprovides an effective and user-friendly CRISPR/Cas9 procedure that significantly improves the genome editing toolbox for fission yeast.