In today's society, many women wear high-heeled shoes. However, the effect that shoes of different heel heights have on the biomechanics and energy cost of gait has not been fully investigated. In the present study, the energy cost and the lower extremity mechanics in shoes of different heel heights (1.25 cm, 3.81 cm, 5.08 cm, and 7.62 cm) were examined in 15 female subjects, seven of whom could be considered experienced high-heel wearers. Kinematic data from high-speed video and kinetic data from a force platform were collected to describe lower extremity mechanics while subjects walked overground at a speed of 4.2 km/hour. Heart rate and oxygen consumption were monitored while subjects walked on a treadmill, also at 4.2 km/hour. There were no significant differences in any of the parameters as a function of experience in wearing high heels; therefore, the data were pooled for further analysis. Analysis of the biomechanical data revealed that ankle plantar flexion, knee flexion, vertical ground reaction force, and the maximum anteroposterior braking force increased as a function of heel height. In addition, the timing of the subtalar and knee joint action was asynchronous with the increase in heel height. Metabolically, heart rate and oxygen consumption also increased with heel height. There were many significant differences between the 5.08-cm and the 7.62-cm heel conditions. Therefore, to maintain comfort and decrease the risk of injury, women may be advised not to wear shoes with a heel height greater than 5.08 cm.