''I'm consulting to HP right now, and although I can't speak for the organization it seems to me that ClearCase is not heavily used here. SourceSafe and other MS tools seem to be most common. I have heard that the need for a fulltime ClearCase administrator is one of the reasons for this.'' -- PeterMerel

Well, if you frequent the ClearCase users mailing list, it is quite clear that ClearCase is indeed ''very heavily'' used at HP. That doesn't mean every conceivable nook and cranny of HP uses it, or even uses it exclusively. But I personally know of at least a dozen shops (some pretty large) inside of HP that use ClearCase, and have heard these folks speak of still other HP groups that do as well. --BradAppleton

Wells Fargo uses it heavily as well.

I use it at Magma Design Automation. -- JeffBell

LockheedMartin uses it, because many government clients demand its use. I've never heard a good reason why. I suspect it's JobProtection at the GovernmentScale. We have several full-time ClearCase admins.  -- DaveFayram

Credence Design Systems uses it.

TektronixInc uses it.

3Com http://www.3com.com uses it (as of April 20, 2004)  

BACS uses it.

Oracle RDBMS development use a modified version of ClearCase.

MCI uses it, and staffs one full-time administrator for it.

Nokia and GE Healthcare use it.

Spx Service Solutions (OTC) uses it.

TI uses it heavily.

Motorola uses it as a standard SCM company-wide.

SIEMENS A.G. uses it in Automation & Drives