Google drops many pages on my site

Indexed pages drops from 3970 to 304

[mt_biker]

Google recently dropped the number of pages indexed on one of my sites from 3970 to 304 (when doing an allinurl: search).

I used a Google cache tool to determine if it was just one datacenter, but it's all of them. Oddly, the search phrases I track are doing better than they have in a long time.

Is this some sort of anamoly or does this happen to other webmasters for no apparent reason too? What expectations can I have for getting my pages back?

[tedster]

the search phrases I track are doing better

That's the key then -- if you're not missing traffic, don't panic.

I would suggest checking that nothing is wrong -- that the urls that went missing are still linked in and spiderable. Then you just need to wait, and maybe look at the linking structure and see if you can tweak it for any important deep pages that have gone missing.