In recent years the practice of yoga has gained popularity as a form of physical fitness and exercise, and has been said to improve strength and flexibility. The main objective of this research project was to evaluate the effects of a six week Iyengar yoga intervention on flexibility. N = 16 low to moderately active females (52.37 +/- 7.79 years) attended Iyengar yoga practice for a total of 6 weeks, consisting of one 90 min session per week. Lumbar and hamstring flexibility were assessed pre and post-intervention using a standard sit and reach test. The results show a significant increase in flexibility, indicating 6 weeks of single session yoga training may be effective in increasing erector spinae and hamstring flexibility. This is important when considering that much of the population find it difficult to attend more than one session a week into their training schedule.