How do you return results from a table where the fields have null value in them

I am trying to see how many records exist in my database based on a field selection.  When I use the following select command in SQL Enterprise Manager no records are returned yet if you tell SQL Enterprise manager to open table is shows you all the rows with a NULL value in the field.  Can someone tell me what I am doing wrong?

select * from dbo.patients where imported = NULL

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