Hájek won three more Challengers during the year including two major ones in Prostějov where he got a retirement victory over Tomáš Berdych and Braunschweig defeated Fernando Vicente in straight sets.

In addition to the three Challenger titles, Hájek made his debut at Grand Slam level where he defeated Lukáš Dlouhý in straight sets before losing to Fernando González.

Hájek was unable to follow up the previously successful year in 2007, but he achieved his best result at Grand Slam level, where he made the third round at Roland Garros where he defeated Thomas Johansson and Bohdan Ulihrach before retiring against Marcos Baghdatis with a shoulder injury.

He repeated his 2006 victory in Prostějov this time as a qualifier defeating Belgian Steve Darcis in the final and former top 10 player Ivan Ljubičić in the quarter-finals.

He also made his debut in the Czech Davis Cup team in the semi-final tie against Croatia where he defeated Roko Karanušić and also played in the final losing to Rafael Nadal.