Sharapova pulled out of the German Open for the second year running, without giving a specific reason, while tenth-ranked Hantuchova is suffering from a stress fracture to her foot.
Despite the withdrawals, the WTA event still boasts a strong field with Belgian world number one Justine Henin, as well as defending champion Ana Ivanovic of Serbia, second in the WTA rankings, confirming their appearances.
"I'm really disappointed to be unable to play at the German Open," said Sharapova, who won her third Grand Slam title at the Australian Open earlier this year. "I'm working hard to get back on court as quickly as my body will allow and I'll be looking forward to playing at the event in the future."
Hantuchova, who reached the semi-finals at the Australian Open earlier this year, said the injury to her right foot needs more time to heal.
"I'm very disappointed that I have to withdraw," she said. "But unfortunately, the stress fracture in my right foot hasn't completely healed. "I'm hoping for a quick recovery and I wish the tournament, its organizers, sponsors and fans a great week of tennis."
Seven of the world's top ten players will be in Berlin including Jelena Jankovic of Serbia, American Serena Williams plus Russians Svetlana KuznetsovaAnna Chakvetadze and Elena Dementieva.