Soil setup effect is a natural phenomenon where pile bearing capacity increases over time as a result of dissipation of excess pore water pressure as well as soil aging. Soil setup significantly contributes to the increase in shaft bearing capacity of prefabricated displacement piles installed in saturated clay. The past experiences indicate that shaft bearing capacity increases almost linearly with the logarithm of time elapsed after the pile initial drive, usually quantified using a dimensionless setup factor. The magnitude of setup factor is governed by pile geometry and type of surrounding soil. To quantify the setup rate potential, a minimum of two field measurements of the pile ultimate load are required. Whenever signal matching analyses are performed on pile dynamic load test results at end-of-drive and restrike data, the variations of setup effects along the pile shaft can be determined. The main objective of this paper is to evaluate the effects of over-consolidation ratio (OCR) on setup factor using pile dynamic load tests (DLT) at end of initial drive and restrike as well as static load tests (SLT). For this purpose, an elaborate field testing program was conducted at Bidboland II Gas Refinery site. The program consisted of DLT and SLT on the prestressed spun concrete piles that have been driven at different locations of the site having variations of OCR as a result of preloading under different surcharge pressures. Results indicate that shaft resistance has considerably increased over time at the study site. The setup factor is affected by the over-consolidation ratio in such a way that with increasing OCR, the setup potential has reduced. The findings of the study are useful in engineering applications of piling in clayey deposits in which the time constraints of construction does not allow performance of dynamic load tests at different time steps as well as estimating the setup factor at sites having over-consolidated soil.