Thinking about acquiring a monkey to keep as an adorable pet? Think carefully. Thousands of nonhuman primates are hosted as companions in people's homes across the United States—relationships that often end in tears.

As babies these big-eyed, furry creatures may seem harmless. But once they reach sexual maturity, experts warn, monkeys can become aggressive. And some primates harbor deadly diseases, like herpes B, that they can pass on to human primates via bites and scratches.

Many people remain undaunted by the risks of adopting primates in their homes. Viewed as status symbols or substitute children, monkeys are commonly sold for thousands of dollars through newspaper ads and the Internet.

"We're looking for a baby monkey to love and spoil," writes one woman from