The concept of time-cost relationship in construction projects was first introduced by Bromilow, using the data of the 328 superstructure projects completed in Australia. The aim of this study is to determine the time-cost relationship of superstructure projects in Turkey. Time and cost data of 460 superstructure projects completed between the years of 1999-2018 was used in the study. Data was grouped primarily on the basis of the intended use of buildings (individual buildings, educational buildings, hospitals, industrial buildings and social housing), and then time-cost relationships were separately determined for each group through statistical analysis. In addition, the effects of the parameters such as exchange rates and the number of non-working days on the time-cost relationship were investigated statistically, as well. As a result of this study, highly meaningful time-cost relationships (R 2 =0,60) are determined for the construction projects in Turkey, excluding disaster relief projects, which is not part of this study. It has also been determined that while the hospital projects in Turkey have the highest coefficient of determination (R 2 = 0,87), social housing projects have the lowest (R 2 = 0,54).