How many extrasolar planets are there?

443.

The Extrasolar Planets Encyclopaedia reports that there are 443 planets outside of our solar system, known as extrasolar planets, that have been detected as of March 19, 2010. Among these 38 were discovered from January to March 2010 alone. These planets range in size from twice the size of Jupiter to one-one hundredths the size of Earth.