Abstract: Nitrogen (N) is one of the important elements for optimum growth as well as high yield in oil palm plantation industry. Hence, estimation of N content in plant tissue is crucial for plantation management to minimize cost of production to produce high yields. Conventional method such as foliar analysis is expensive and not a real time analysis. Implementation of chlorophyll meter and spectral approaches has been used widely in estimation of N in various types of crops but a few studies have been carried out with regard to oil palm. Therefore, this study was conducted to evaluate multiple proximal sensors for N estimation in mature oil palm. The experiment was conducted in a plantation setup in Randomized Complete Block Design (RCBD) with three replications. Three levels of N treatments; 0, 1 and 2 kg N per palm per year as ammonium chloride were applied in split applications within two different planting years’ plots. The data was collected in February and October 2014. The combination of physiological and spectral models fit the best (R2 = 1.00) for foliar N or N rate estimation in matured oil palm. Generally, SPAD meter was not suitable to estimate N content in matured oil palm leaves but the function can be compensated by the spectroradiometer. The variation of single and combination of single physiological or spectral models in estimating N was highly influenced by age and sampling time. Palm stem diameter was important in this study though it is not sensor-measured.