You can use below references:
http://blog.sonomapartners.com/2011/06/simple-javascript-to-create-dynamic-cascading-picklists-in-microsoft-crm-2011.html
http://community.dynamics.com/crm/b/sonomapartners/archive/2011/06/16/how-to-use-javascript-to-create-dynamic-cascading-picklists-in-microsoft-crm-2011.aspx
Hope this helps. ----------------------------------------------------------------------- Santosh Bhagat If this post answers your question, please click "Mark As Answer" on the post and "Vote as Helpful"