Nintendo of America president Reggie Fils-Aime has said that the 3DS has "no health issues" - except maybe for kids under seven.
"We will recommend that very young children not look at 3D images," Fils-Aime said at E3 yesterday.
"That's because, [in] young children, the muscles for the eyes are not fully formed."
"This is the same messaging that the industry is putting out with 3D movies, so it is a standard protocol. We have the same type of messaging for the [1990s Nintendo virtual reality machine] Virtual Boy, as an example."
With much of Nintendo's portfolio being very kid friendly, this could come as a surprise to some.
We haven't tested the 3DS on a six year old, but if you want our general verdict read our Nintendo 3DS review.