Weight cutting is a common practice in amateur boxing with the purpose of taking advantage of rivals competing in weight divisions below the athlete’s normal weight. Dehydration is a common weight–manipulating technique in boxing, and is known as a serious health-threatening behavior. In this study, we investigated field hydration status differences between the weight class categories in elite junior boxers. The sample of subjects comprised 21 male junior boxers from Croatia, Germany and Hungary (all national team members). The field assessment was conducted prior to competition. Subjects were divided into three weight class categories: (Lw), (Mw) and (Hw). The sample variables included urine specific gravity (USG) measured via a refractometer and total body fluid content (BFC) measured via bioelectric impedance analysis (BIA). Data were collected on two occasions, i.e. at national team competitions that took place in preparation for the World Junior Championships. The results show that there was a statistically significant difference between Lw 1.027±0.004 and Hw 1.019±0.005 (F=8.81, p < 0.001) and Mw 1.028±0.003 and Hw (F=7.16, p<0.01) in USG. BIA findings showed conflicting results in relation to the USG findings. The results show a significant difference between Lw 67.84% BFC and Hw 65.14% BFC (p<0.01). These conflicting results, the lack of correlation between the two methods and the discrepancy in the Bland–Altman plot indicate that techniques for non–invasive field assessments of hydration have certain limitations. It seems that RF is more sensitive and accurate diagnostic tool to detect body fluid shifts then BIA when applied on athletes involved in chronicle weight cycling protocols. Nevertheless, our data suggest that Lw and Mw class athletes seem to be more prone in reaching consequent dehydration state that literature frequently cites as hypohydration.