Here are a few questions/ suggestions about what might be causing this issue: 1) Are you using the same version of IDL across all these systems? 2) Are both these systems the same OS and version? 3) Perhaps the file was corrrupted when copied from one machine to another. Perhaps you could try sending another copy from the machine where it is working to the failing machine and see if that helps with the issue. 4) Is the file located on a shared network directory. If this is the case, I wonder if IDL might be having trouble reading the file from this type of location on some of your systems. 5) Could you add a break point and then step through the "read_dicom" call on one of the machines where the call is failing? David Starbuck Harris - GS