"We look forward to treating everyone to a free cup of our delicious, freshly brewed iced coffee to celebrate the arrival of spring," said Robert Rodriguez, Dunkin' Donuts brand president. "As the category leader, Dunkin' Donuts has been brewing iced coffee for more than 25 years and we are thrilled to be kicking off another iced coffee season with this all day, nationwide event."

Iced coffee is fast becoming as "hot" as the classic cup at Dunkin' Donuts. While iced coffee sales typically spike in summer months, Dunkin' Donuts has seen rapid growth year-round, including during the winter months. Iced coffee is the second most frequently sold product after hot coffee at Dunkin' Donuts.

According to NPD CREST data, Americans drank more than 450 million servings of iced coffee in restaurants in 2006 — a 16 percent increase from 2005 — and Dunkin' Donuts sold more than 150 million servings of iced coffee last year.