Generally, the answer is no; nationals from the US are allocated a thirty-day visa-free stay in Macau upon arrival. European and Japanese nationals are allowed ninety days visa-free stay, and UK nationals six months. As with most countries, you will need six months' validity on your passport. If you intend on doing business in Macau, as an increasing number of people are, you will need to apply for a business visa at your nearest Chinese consulate.
Thanks for letting us know!
Tell us why!