I don't have a SQL Server installed and none to connect to (this is a truly strange and scary feeling, but has to do with me reinstalling my at-home-server) but I would imagine a foreign key that is created, relating two tables already in the diagram would show up next time you open the diagram. Why don't you try it? Go to AdventureWorks, Pubs or even TempDB. CREATE TABLE t1 (id int identity(1,1) primary key, f varchar(10)) CREATE TABLE t2(id int identity(1,1) primary key, t1_id int) Create a new diagram with the two tables, save it and close it. Do ALTER TABLE t2 ADD CONSTRAINT FK_t1_t2 FOREIGN KEY (t1_id) REFERENCES t1(id) Open the diagram again. Did the relation show up? Like said - if I had a SQL Server around I'd check it myself.