Apple has apologised for a "deeply offensive" iPhone application called Baby Shaker, which made a game of quieting crying babies by shaking them.
It removed the $0.99 (£0.59) game from its iTunes Store on Wednesday, two days after it went on sale.
It sparked outrage from children's groups and brain injury foundations.
The aim of the game was to quieten babies by shaking the iPhone until a pair of thick red Xs appeared over each eye of a baby drawn in black and white.
"This application was deeply offensive and should not have been approved for distribution on the App Store," Apple said in a statement.
"We sincerely apologise for this mistake and thank our customers for bringing this to our attention."
But an Apple spokeswoman would not comment on why the program - developed by a company called Sikalosoft - was approved for sale in the first place, nor how many people had downloaded it.
The iTunes description included the line: "See how long you can endure his or her adorable cries before you just have to find a way to quiet the baby down!"
It also included a disclaimer: "Never shake a baby."
Officials from Sikalosoft were not available for comment.
US-based organisations which seek to prevent brain injuries from Shaken Baby Syndrome (SBS) - including the National Centre on Shaken Baby Syndrome and the Sarah Jane Brain Foundation - condemned Apple for approving the game's sale.
Jetta Bernier, executive director of Massachusetts Citizens for Children, said: "I am disheartened that with this new application Apple is encouraging frustrated adults to shake infants, not only to end their crying, but to end their lives.
"There are many effective infant soothing strategies that adults can use to calm their fussy, crying babies. Shaking is not one of them," the Daily Telegraph reported her as saying.
The outrage over Baby Shaker came as Apple celebrated the one billionth download from its App Store, which launched nine months ago.
"The speed with which the App Store has ramped up is impressive and has really set the bar high for everyone else," analyst Van Baker of Gartner told the BBC.
"Everyone from Nokia to Palm and from RIM (BlackBerry) to Google with Android are trying to follow suit. The question remains as to how good a job they will do."
There are more than 35,000 applications in the store. Some are free and the most expensive are $9.99 (£6.82).
Apple has highlighted the most popular applications.
At time of writing a game called Catcha Mouse is top of the free download category with more than one million downloads. In the paid section, the top spot is taken by a game called StickWars.
Apple is rewarding the downloader of the one billionth app with a prize that will total over $13,000. The gift will include a 17" MacBook Pro, iPod Touch, a $10,000 iTunes gift certificate and an Apple Time Capsule.