*Purpose: 1R rejection is commonly seen in routine post-transplant biopsies. While presence of occasional 1R rejection is not considered to be detrimental, the significance of repeated 1R rejection is not well studied.

*Methods: We conducted a retrospective analysis of patients transplanted at our center, between July 2008 and December 2014. A total of 1,128 biopsies were performed in 69 patients. Each patient on an average had 16 biopsies.

*Results: 14 patients had grade 0 on all their biopsies, 22 had grade 1 on one or two of their biopsies, 30 had grade 1 on three or more of their biopsies. Three patients had grade 2 on their initial biopsy and were excluded from the study. Baseline characteristics are summarized in the table. Compared to grade 0, presence of grade 1 rejection and repeated occurrence of grade 1 rejection, did not predict increased risk of mortality or progression to grade 2 or grade 3 rejection. Grade 1 rejection and repeated occurrence of grade 1 rejection did not predict development of de novo donor specific antibodies or graft failure as defined by decrease in ejection fraction to less than 55%.

*Conclusions: Grade 1 rejection or presence of repeated grade 1R was not associated with adverse outcomes. There was no difference in subsequent grade 2 or grade 3 rejection, development of de novo donor specific antibodies, graft failure and mortality in patients with grade 1 compared to grade 0 rejection.

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