Tea Tree Oil is highly effective against mold and mildew. In fact, there is evidence that it has a preventative effect from future mold growth. I had a mold problem a while back and I researched (Google, mostly) on what I should do. I found that a tea tree solution can be made by diluting the oil and putting in a spray bottle. Then, spray away at the mold. Wait a day or two and wipe it away, I did some further research to see if tea tree oil really is effective or if its was just another wive's tale. I did find at least several peer reviewed articles/studies on the efficacy of tea tree oil and thyme oil against mold, (Google Scholar). Needless to say it does work and it worked for me. And hey I love the smell too!