The purpose of this study was to evaluate the changes in the electromyographic (EMG) activity of the trunk and the lower limb muscles during quiet standing on an unstable surface while wearing low-heeled shoes (3 cm), high-heeled shoes (7 cm) and without footwear (0 cm) in 20 young healthy women. The subjects stood on an unstable surface for 30 seconds. We examined the differences in the EMG data of the erector spinae, rectus abdominis, biceps femoris, rectus femoris, tibialis anterior, and the gastrocnemius medialis muscle. A one-way repeated analysis of variance was used to compare the effects of shoe heel height on the EMG activity with the level of significance set at ${alpha}=.05$. The EMG activity of the erector spinae and the rectus femoris were significantly increased (p<.05) in the subjects who wore elevated heel height, while the tibialis anterior and the gastrocnemius medialis were significantly decreased (p<.05). However, the rectus abdominis and the biceps femoris exhibited no significant difference among the three conditions. The above results indicate that wearing high-heeled shoes may change the postural strategy. The findings of this study suggest that excessive heel height could contribute to an increased fall risk during quiet standing.