Hi alexT

Set the [mybinaryfield] field for accepts null values, open the table in
Design View and check its *Allow Nulls*
or execute a T-SQL command.
----
Alter table myTable
Alter column mybinaryfield binary(50) null
----
(check the size of binary field)

bye

As others have indicated, if the definition of the field permits Null
values, you should be able to simply assign the value. Here's an example. I
started this code yesterday, when there was some debate about whether the
field in question was binary or bit, so it includes both ...

Public Sub TestSub()

   Dim rst As ADODB.Recordset

   With CurrentProject.Connection
       On Error Resume Next
       .Execute "ALTER TABLE Employees DROP COLUMN TestBit"
       .Execute "ALTER TABLE Employees DROP COLUMN TestBinary"
       On Error GoTo 0
       .Execute "ALTER TABLE Employees ADD TestBit bit Null"
       .Execute "ALTER TABLE Employees ADD TestBinary binary Null"
       .Execute "UPDATE Employees SET TestBit = Null WHERE LastName =
'Davolio'"
       .Execute "UPDATE Employees SET TestBinary = Null WHERE LastName =
'Davolio'"
   End With

   Set rst = New ADODB.Recordset
   With rst
       .ActiveConnection = CurrentProject.Connection
       .CursorType = adOpenKeyset
       .LockType = adLockOptimistic
       .Source = "SELECT * FROM Employees WHERE LastName = 'Fuller'"
       .Open
       .Fields("TestBit") = Null
       .Fields("TestBinary") = Null
       .Update
       .Close
   End With

End Sub

I've never actually worked with binary fields in SQL Server, so I can't
really give you any firm guidance here.  The two other responses to the post
sort of indicate the following, just let me spell it out, and add my own two
cents as well.

First and foremost, make sure the field supports Null values. :)

Second, try using the full syntax, rather than an abbreviated one that
relies on default properties.  In other words, use the .Fields collection,
and the .Value property.  It's rare that these are required, but will
occasionally fix an otherwise problematic piece of code, typically when your
field name happens to be a reserved word.

   rs.Fields("mybinaryfield").Value = Null

Everything I know says that this SHOULD work, but binary fields are a bit of
a special case, so maybe all my typing here is for nothing. :)

Rob

If you're still having problems with this, Alex - what happens when you
execute that code? Is there an error message?