Aim: The aim of this study was to compare serum and gingival crevicular fluid (GCF) levels of fibroblast growth factor 23 (FGF23) in healthy patients with periodontitis versus gingivitis in end-stage renal disease (ESRD) patients undergoing hemodialysis and periodontitis in patients with ESRD undergoing hemodialysis. Materials and Methods: The study design was a cross-sectional analytical study that included a total of 45 patients with periodontal disease that were divided into three groups with 15 in each group. Group I (n = 15) was systemically healthy having periodontitis, group II (n = 15) had ESRD and gingivitis, and group III (n = 15) had ESRD and periodontitis. The clinical parameters for gingivitis and periodontitis, level of FGF in serum, and GCF were all evaluated in the three groups and the results were compared. Results: FGF23 levels in GCF and serum were statistically significantly higher in group III: ESRD with periodontitis (534 ± 92.7) and (448.2 ± 274.5), respectively, followed by group II: ESRD with gingivitis (150 ± 33.4) and (242.1 ± 31.1), respectively, while were significantly lower in group I: healthy patients with periodontitis (53.7 ± 8.1) and (52.9 ± 6.3), respectively, with a significant difference between the three groups with P < 0.001. Conclusion: Periodontitis patients on hemodialysis showed higher clinical scores (plaque index, bleeding on probing %, pocket depth, and clinical attachment loss) as compared with their counterparts with free medical conditions. The adverse effect of both periodontal and renal disease on clinical presentation and inflammatory markers were strongly evident by the high serum and GCF FGF23 levels with ESRD having the strongest impact.