There's got to be some way to categorize your list, so the user chooses a category first, narrowing down the list of items to select from. You mention diagnosis, so I assume it's a medical application of some sort. Those types of things are typically categorized by some numbering system. Use that. If you can't do that for some reason, at the very least, organize the list alphabetically and have them click on a letter to bring down only those items.

~~Bonnie

>My customer needs to select a diagnosis from a list of 11,000. Do you have any ideas how to break up a single simple list, into logical components that the customer can choose from? Or is there some other type of way to work with this data?
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>I am struggling with the large dataset. Maybe there is another logical way to display the data or search the data that I am not seeing.