Hi all, May I know - how to delete a large no. data outside or inside a boundary in a dwg file?RegardsRKM 

Depends on the boundary.  Post an image.

If you are using Autodesk's Civil 3D or Map 3D the MAPTRIM command may work for you...

In plain AutoCAD you could make use of the Express Tools command called EXTRIM.EXTRIMTrims all objects at the cutting edge specified by a selected
Polyline, Line, Circle, Arc, Ellipse, Text, mtext, or Attribute Definition. It works only from the command line.

I would suggest searching at the AutoDesk Forums, http://forums.autodesk.com/, where I think this kind of thing has come up before, using Search terms such as "erase outside" and "erase inside" and other related wordings.

Thanks JohnActually It is not trimming of objects, it is deletion/erase of large no. of points outside a boundary.May be you can suggest another tool. RegardsRKM

Since the objects are trimmed to the extents of the boundary they would not exist anymore.

Thank you very much - MAPTRIM command is working to my satisfaction.RegardsRKM

Since MAPTRIM is not a command found in AutoCAD then I guess you are actually using an AutoCAD vertical product.

Yes, I worked in Civil 3D as suggested by one of the members.RegardsRKM 

It's always helpful to know what program someone is using when a question is being posted.