A large number of reinforced concrete buildings collapsed or were heavily damaged during the 7.4 magnitude earthquake that struck northwestern Turkey on August 17, 1999. Recorded peak ground accelerations were relatively low (0.3 g–0.4 g) compared to the magnitude of the structural damage, and the elastic acceleration response spectra from the recorded motions were comparable with the elastic design spectra specified in the current Turkish seismic code. Seismic code requirements are discussed and compared with observed details. Many structural deficiencies were highlighted by the earthquake damage, including: reinforced concrete columns with insufficient confinement and transverse reinforcement, 90-degree hooks at the end of column ties, poor detailing in beam-column joint regions, strong-beam and weak-columns, soft and weak stories, and poor quality construction. Buildings with shear wall structural elements generally performed well On August 17, 1999, a Mw 7.4 earthquake occurred on the 1500-km-long North Anatolian fault in northwestern Turkey. The epicenter of the earthquake was near Izmit, 90 km east of Istanbul (Fig. 1). Following the earthquake, the Pacific Earthquake Engineering Research Center dispatched a reconnaissance team to the epicentral region to learn first hand about the performance of the civil infrastructure. The geographic region that was impacted by the earthquake was somewhat narrow banded and centered around the fault, and stretched from Istanbul in the west to Go ¨lyaka and Du ¨zce in the east. Damage to building construction was severe and left homeless. Some 77,300 homes and businesses were destroyed, and 244,500 were damaged. The majority of deaths and injuries were in the cities of Kocaeli, Sakarya, and Yalova. This paper describes briefly the state-of-practice for building seismic design and construction in Turkey, and compares the US and Turkish codes. The performance of the reinforced concrete frame and wall buildings and their components during the 1999 Kocaeli earthquake is presented, and evaluated considering the seismic design and construction practice in the epicentral region