This is a BIG question.  About 50% of all AIDS patients in North America are homosexuals or bisexuals.  \n\nNaturally, you can do the math to see that a gay person has much higher odds.  However, this disease first moved through the gay community and later to the straight.  So, the number of AIDS patients is not the same data as the number currently getting infected.\n\nTo further complicate things, these stats are drastically different from country to country.\n\n\nBottom line:  \n\n1.  Anal sex if physically more vulnerable to HIV contraction than vaginal.\n\n2.  Permiscuity is a major factor, obviously.  Gay or striaght, be careful who you sleep with.\n\n3.  Straights are catching up, especially in other parts of the world.