<p>To evaluate the treatment success and reversal rate of corneal allograft rejections in post-penetrating keratoplasty patients. Retrospective cohort study was performed in post-penetrating keratoplasty patients treated for corneal allograft rejection between September 2015 and August 2024 in a tertiary eye center in Debrecen, Hungary. Indication of keratoplasty, onset of the allograft rejection, best corrected visual acuity (BCVA), corneal transparency on slit lamp examination and applied treatment were recorded. In our institution’s patient registry, 68 allograft rejection episodes were found. Before the rejection, all grafts were completely transparent. The rejection episodes occurred median 21&#xa0;months after surgery. Diagnosis and treatment took place median 5&#xa0;days after the onset of symptoms. Allograft rejection could be successfully reversed in 48 of the total 68 cases (70.6%). Treatment was adjusted individually and all patients received local treatment; 16 received only local and 52 received combined systemic and local corticosteroids resulting in a similar rejection reversal rate (13/16 vs. 35/52; <i>p</i> = 0.359). Comparing first (47) and repeat grafts (21), there were no significant differences between the treatment success rate (33/47 vs. 15/21; <i>P</i> = 1.000) and the frequency of combined local-plus-systemic treatment (34/47 vs. 18/21; <i>p</i> = 0.355). Before the rejection episodes, BCVA was 0.40 ± 0.30, which decreased following the rejection (0.28 ± 0.28; <i>p</i> &lt; 0.001). This reduction in BCVA was observed in successfully treated cases as well (0.44 ± 0.28 vs. 0.38 ± 0.27; <i>p</i> = 0.008). Our dexamethasone-based local treatment demonstrated similar effectiveness in reversing corneal allograft rejections in patients underwent penetrating keratoplasty compared to data on prednisolone by other studies. However, systemic steroid augmentation might be needed more frequently when using topical dexamethasone.</p>