I created a group in Facebook.
Now I want to change it to a fan page and retain the group members as fans.
Is there a way to accomplish this ?
Unfortunately, no. From the Facebook Help pages:
"It is currently not possible to convert Facebook groups into Pages. We recommend that you create a Page and notify your group members about it. Note that you will not be able to send your group a message if your group has more than 5,000 members."