Stopping Spam Site Registrations

Hey Guys,
I am in need of some help here. Wondering if you can help me figure out a way to stop the spam site registrations that I am getting. I have been researching some options online and am not sure what direction to go.
Thanks!
Tony
Here is what they look like:

New user registration on your site BMC Academy - Barlow/McCarthy - Physician Relations, Physician Recruitment Education:

Username: Ros***********

E-mail: and********@mail.ru