Disclosed and claimed are mutation(s) or modification(s) of the CRISPR enzyme, for example a Cas enzyme such as a Cas9, which obtain an improvement, for instance a reduction, as to off-target effects of a CRISPR-Cas or CRISPR-enzyme or CRISPR-Cas9 system or complex containing or including such a mutated or modified Cas or CRISPR enzyme or Cas9. Methods for making and using and uses of such mutated or modified Cas or CRISPR enzyme or Cas9 and systems or complexes containing the same and products from such methods and uses are also disclosed and claimed.