The present invention relates to blends of encapsulated biocides with free biocides. In particular, the present invention relates to blends of encapsulated 4,5-dichloro-2-n-octyl-3(2H)-isothiazolone ("DCOIT") with free biocides. The invention also relates to marine antifouling coatings and paints incorporating free biocides and encapsulated DCOIT, and using the free biocides and encapsulated DCOIT in marine antifouling coatings and paints.