en Geotechnique Geotechnique Research Paper Research Paper Three common approaches to determine the axial pile capacity based on static analysis and in-situ tests are presented, compared and evaluated. The Unified Pile Design (UPD), American Petroleum Institute (API) and a SPT based methods were chosen to be validated. The API is a common method to estimate the axial bearing capacity of piles in marine environments, where as the others are currently used by geotechnical engineers. Seventy pile load test records performed in the northern bank of Persian Gulf with SPT profile have been compiled for methods evaluation. In all cases, pile capacities were measured using full scale static compression and/or pull out loading tests. As the loading tests in some cases were in the format of proof test without reaching the plunging or ultimate bearing capacity, for interpretation the results, offset limit load criteria was employed. Three statistical and probability based approaches in the form of a systematic ranking, called Rank Index, RI, were utilized to evaluate the performance of predictive methods. Wasted Capacity Index (WCI) concept was also applied to validate the efficiency of current methods. The evaluations revealed that among these three predictive methods, the UPD is more accurate and cost effective than the others. Pile, Axial Bearing Capacity, Full scale load test, Predictive methods efficiency, Wasted capacity index (WCI) 45 54 http://ijce.iust.ac.ir/browse.php?a_code=A-10-270-2&slc_lang=en&sid=1 A. Eslami afeslami@yahoo.com 180031947532846006319 180031947532846006319 Yes Amir Kabir University of Technology I. Tajvidi iman_de_0062@yahoo.com 180031947532846006320 180031947532846006320 No Islamic Azad University, Central Tehran Branch M. Karimpour-Fard Karimpour_mehran@iust.ac.ir 180031947532846006321 180031947532846006321 No he university of Guilan