Strong evidence for a link between the follistatin gene and polycystic ovary syndrome (PCOS) has recently been found in a well-designed large-scale study. Follistatin binds to activin and affects its functions, e.g. stimulation of FSH synthesis and secretion. Thus, it may play a role in the functional impairment of the FSH-granulosa cell axis in PCOS. In this study, we screened 64 Chinese patients with PCOS for mutations in the entire coding region (including the region encoding alternative carboxy-terminals) of the follistatin gene using polymerase chain reaction (PCR)-based single-stranded conformational polymorphism (SSCP) and DNA sequencing. However, we could not identify a single mutation of either the activating or inhibiting type, using these techniques. Therefore, it would appear that PCOS in the local Chinese population is not caused by mutations in the coding regions of the follistatin gene.