Background: Hirsutismis the presence of excess body or facial terminal (coarse) hair growth in females in a male-like pattern, affects 5-15% of women, and is an important sign of underlying androgen excess. Different methods are available for the assessment of hair growth in women. Methods: We conducted a literature search and analyzed the published studies that reported methods for the assessment of hair growth. We review the basic physiology of hair growth, the development ofmethods for visually quantifying hair growth, the comparison of thesemethods with objective measurements of hair growth, how hirsutism may be defined using a visual scoring method, the influence of race and ethnicity on hirsutism, and the impact of hirsutism in diagnosing androgen excess and polycystic ovary syndrome. Results: Objective methods for the assessment of hair growth including photographic evaluations andmicroscopic measurements are available but these techniques have limitations for clinical use, including a significant degree of complexity and a high cost. Alternatively, methods for visually scoring or quantifying the amount of terminal body and facial hair growth have been in use since the early 1920s; these methods are semi-quantitative at best and subject to significant inter-observer variability. The most common visual method of scoring the extent of body and facial terminal hair growth in use today is based on a modification of the method originally described by Ferriman and Gallwey in 1961 (i.e. the mFG method). Conclusion: Overall, the mFG scoring method is a useful visual instrument for assessing excess terminal hair growth, and the presence of hirsutism, in women. © The Author 2009. Published by Oxford University Press on behalf of the European Society of Human Reproduction and Embryology.