The current paper presents a back analysis of field pile load-settlement relationships using commercial finite element program “PLAXIS”. Five driven piles, two continuous flight auger piles of diameters 0.40 m and 0.60 m and two bored piles of diameters 1.00 m, 1.80 m were used in the analysis. The study aims to investigate finite element parameters which control the load - settlement relationship for small diameter piles (Diameter ≤ 600 mm) and large diameter piles (Diameter > 600 mm) and to search for the matching values to test results. It is shown that the value of the interface factor ( Ri ) between pile and soil affects the load-settlement relationship for small diameter piles. For larger diameter piles results confirmed that the value of the lateral pressure coefficient (K) and the value of soil compressibility modulus (Es) have strong effect on the pile load-settlement behaviour.