One in six couples experience difficulties conceiving, with male factors present in approximately half of all cases. The major factor affecting natural conception is probably ability of sperm to reach the egg, with only 8-20 sperm from over 200 million ever reaching the egg even in fertile couples. As yet there is no successful drug treatment targeted to improve male fertility. The best hope for rational therapy will derive from a detailed understanding of sperm energetics and this can only be achieved through detailed analysis of the sperm's swimming dynamics. This programme will provide detailed 3-dimensional movies of swimming sperm, offering new insights into sperm dynamics that will enable next generation individualised diagnostics and the rational screening of new drug treatments.