Visa, Inc. (NYSE: V) announced their financial results for the Company’s fiscal second quarter 2010 (which ended March 31, 2010). Visa showed strong earnings growth, and their prepaid and debit transaction growth continues.

In their earnings call, Visa CEO Joseph Saunders remarked that “the number of Visa debit and prepaid Visa cards issued globally surpassed one billion for the first time in our history. This represents not only further penetration of debit globally but the underlying growth and importance of prepaid cards, which are a key contributor of all of our debit business overall.”

While Visa does not break prepaid debit numbers out separately from regular debit numbers, Mr. Saunders suggested that they may start doing so in the near future.

The number of debit cards issued as well as the volume of debit card transactions increased at double digit rates from the previous quarter and year. For example, comparing the quarter ending December 2009 with the same period in 2008, the total number of debit cards issued with the Visa brand increased by 13% (to over 1 Billion cards). Credit card numbers for the same period showed a drop of 4%.

Debit payments volume for the same period showed a growth of almost 20% (while credit payments during the same period grew by 11%).

Clearly, debit transactions and debit cards are a material piece of Visa’s growth. We can’t wait to see the prepaid debit card numbers broken out separately from the total debit card numbers.

Check out the Visa earnings release here, and the investor presentation here.