Flaxseed is a rich source of lignan and has been shown to reduce androgen levels in men with prostate cancer. Polycystic ovarian syndrome (PCOS), a common endocrine disorder among women in their reproductive years, also is associated with high levels of androgens and is frequently accompanied by hirsutism, amenorrhea and obesity. This clinical case study describes the impact of flaxseed supplementation (30 g/day) on hormonal levels in a 31-year old woman with PCOS. During a four-month period the patient consumed 83% of the flaxseed dose. Heights, weights, and fasting blood samples taken at baseline and 4-month follow-up indicated the following values: BMI (36.0 vs. 35.7 m/kg2); insulin (5.1 vs. 7.0 uIU/ml); total serum testosterone (150 ng/dl vs. 45 ng/dl); free serum testosterone (4.7 ng/dl vs. 0.5 ng/dl); and % free testosterone (3.1% vs. 1.1%). The patient also reported a decrease in hirsutism at the completion of the study period. The clinically significant decrease in androgen levels with a concomitant reduction in hirsutism reported in this case study demonstrates a need for further research of flaxseed supplementation on hormonal levels and clinical symptoms of PCOS. Copyright © 2007 by New Century Health Publishers, LLC. All rights of reproduction in any form reserved.