different and that these differences may be "hard-wired" by true biological differences that may relate to hormonal effects, to differences in anatomy or to differences in genetic susceptibility. However, they may also be due to differences in exposure that may be culturally related, different approaches to disease, including greater reluctance on the part of women in developing countries to present to healthcare workers or to differences in the way women are treated once they present. An important example of this complexity can be seen in the chapter "Tuberculosis in women". The authors point out that differences between males and females in the recognition and reporting of tuberculosis may be largely due to socioeconomic and cultural differences, but biological mechanisms, such as hormonal or genetic susceptibility, may also be responsible. Thus, the many differences that are being reported between the sexes in all aspects of biology and behaviour are often complicated. Finding the differences and the reasons for them is the first important step. Next, we need to be equally diligent in looking for sex and gender-specific solutions and interventions. INTRODUCTION c