Google is getting out of the porn advertising business.



The changes, which went into effect late Monday, prohibit any promotion of most sexually themed sites, specifically those that feature "graphic sexual acts with intent to arouse including sex acts such as masturbation."



A company spokesperson noted that Google has long had restrictive policies on its adult category for some time and expected many advertisers had already looked to other advertising venues.



Industry insiders, though, tell a different story.



"I was caught by surprise," says Theo Sapoutzis, chairman and CEO of AVN Media Network. "I was one of the very first advertisers for AdWords back in 2002. It's something that's been [untouched] for 12 years, so you don't expect change is going to start happening."



Read MorePorn site sues Amazon over Fire TV name

Notification of the policy change came in an email, sent to companies that were positioned to be in violation of the new policy earlier in June, which read:



Beginning in the coming weeks, we'll no longer accept ads that promote graphic depictions of sexual acts including, but not limited to, hardcore pornography; graphic sexual acts including sex acts such as masturbation; genital, anal, and oral sexual activity.



When we make this change, Google will disapprove all ads and sites that are identified as being in violation of our revised policy. Our system identified your account as potentially affected by this policy change. We ask that you make any necessary changes to your ads and sites to comply so that your campaigns can continue to run.



Adult industry insiders say the impact of Google's decision won't be clear for some time. While many companies use AdWords, word of many adult sites—ranging from streaming video "Tube" sites to webcam models to entertainer's personal pages—spread through word of mouth and by natural search results. (Related: Top Adult Entertainers)



"There are many people who say the biggest losers are the ones who play by the rules," says Tom Hymes, senior editor at industry trade publication AVN. "The winners are the huge properties with a lot of free content and frequent updates—the type of actions the Google algorithms really like. But at the end of the day, there are some people out there who have been abiding by every [rule] that Google sets and they're getting cut off at the knees now."