Male fertility has hardly been considered in the demographic literature. Theories formulated to explain changes in human fertility have seldom included men and empirical analyses of fertility have been characterised by a strong female-dominated tradition (Zhang 2011). Recent bio-medic literature suggests that increasing male age is associated with a decline in semen volume, sperm motility, and sperm morphology. Furthermore, significantly lower fecundability has been found even after controlling for maternal age and other confounding variables. Other factors, such as a good heath status, can be crucial in male fertility and fecundability. In this paper, we study this topic in a historical context. In particular, using detailed individual biographies that cover the whole reproductive life course, we calculate and compare male and female age-specific marital fertility rates for the Sardinian town of Alghero in the period 1866-1935. Thanks to micro-level analyses, we test the hypothesis that the “male effect" was more pronounced when health, and more in general the quality of life, was low. We find a crucial effect of male age (especially after the age of 50) and this is particularly true for the poorest and unhealthy individuals.