This happens a lot. Ill make a complex mesh, and edge split sort of fixes some of the definition that smooth ruins, but it also makes hundreds of little holes in my mesh. Pretty much happens to any complex surface, most recently, a mountain range.
Can this be fixed?
I assume you’re using a Subsurf modifier after the Edge Split?
If so, that’s to be expected. Edge Split does exactly what its name says: It divides certain polygons along their edges. The following Subsurf pulls those separated polygons together - individually, as they are no longer connected to their respective neighbors - hence creating the holes.
Try using Auto Smooth instead of Edge Split.
If that’s not what you meant, please supply an example .blend file or - at the very least - a screenshot.
Something similar happens to me on some imported models, in general the fix for me is to remove doubles, after that edge split works most of the time.
Edge split has other purpose. It quite literally splits/detatches/rips the marked edges (or by angle).
If you want hard edges that behave nicely after SubD modifier, add Bevel modifier before it and play with parameters to get desired result.
You can also explore Creasing.