<p>Nitrogen use efficiency is a trait of agronomic importance due to its relevance for optimizing fertilizer use and reducing environmental impacts. In Colombia, potato growers commonly apply excessive nitrogen fertilizer rates to maximize yields. However, this practice often results in low nitrogen use efficiency and substantial nitrogen losses to the environment, contributing to pollution. In this study, nitrogen use efficiency was evaluated in the diploid potato variety Criolla Colombia, which belongs to the <i>Solanum tuberosum</i> Group Phureja. This group has been underrepresented in nitrogen efficiency studies, making this research a novel contribution to the understanding of nitrogen dynamics in these genotypes. Six nitrogen doses were applied to plants cultivated in an organic-mineral substrate under greenhouse conditions. Variables related to nitrogen uptake and utilization were assessed, including plant biomass, leaf area, nitrate content in sap, and relative chlorophyll content. These variables increased with higher nitrogen doses, while the highest nitrogen use efficiency and agronomic nitrogen use efficiency were observed at the lowest nitrogen levels. The physiological and biochemical responses of the plant to nitrogen variation enabled the phenotypic profiling of this trait. These findings provide valuable insights into nitrogen dynamics in diploid Phureja potatoes and offer useful guidelines for nitrogen management and the development of selection criteria in potato breeding programs aimed at improving nutrient use efficiency.</p>