The woman who kills her battering mate and claims self-defense must show the relevancy of expert testimony to her perceptions of imminent danger. Once this has been shown, the specific requirements governing the admissibility of expert testimony must be addressed. Courts react differently in each case, as they must, depending on the circumstances of the killing and the trial. Increasingly, evidence on battered woman syndrome is allowed to reach the jury. This may be due to a steady rise in the volume of scholarly literature which demonstrates a greater acceptance of the syndrome. Regardless of the reasoning used by the courts to allow or disallow the testimony, the battered woman syndrome is not a defense. It is highly relevant evidence, introduced by an expert, that may help a jury to understand that a woman's perception of imminent danger was reasonable under the circumstances. Evidence of the syndrome does not indicate insanity but establishes the existence of a battered woman's heightened sensitivity to danger. 186 footnotes.