As we know MSCRM 2011 provides OOB related lookup filtering feature. Let’s take an example I have two lookup in opportunity form, Customer (Account) and Contact. and I want to filter primary contact lookup based on Account selected. I want to only show only those contacts where Parent Account is selected account.

I have created two accounts Test1 ,Test2 and created three contact where two contacts related to Test1 and one contact
related to Test 2.

Before Filtering Setting

I have selected Test1 account and when I will clickon Contact I will get below lookup window

You can see here I can see all contact which is related to Test1 as well as Test2. So let’s set filter criteria

1. Select Customize Tab and select Form.
2. Double Click on contact lookup.
3. Set Related Record Filtering like below

4. Save and publish your changes.

Next time when you will select contact lookup you will only get related contacts like below

After Filtering Setting

Enjoy !!!