In cross flow jets, the presence of kidney-vortices, a pair of counter-rotating vortices, is well known. However, less appears to be known about the simultaneous presence of anti-kidney vortices, whose sense of rotation is opposite to that of the kidney-vortices. The anti-kidney vortices become most pronounced when the jet-hole geometry changes from a round jet to non-circular ones. The origin of the anti-kidney vortices, the effect of their competition with the kidney vortices, and its practical implications will be discussed.