BACKGROUND: Peritubular capillaritis has been associated with chronic rejection, but the characteristics of subclinical lesions in peritubular capillaries are unknown. METHODS: Fifty-three renal allograft recipients underwent a protocol biopsy at both 3 and 12 months after transplantation. Subclinical chronic antibody-mediated rejection (CAMR) at 1 year was diagnosed when three or more of five criteria were present: basement membrane multilayering of peritubular capillaries (MLPTC), transplant glomerulopathy, increase in intimal fibrosis between 3 and 12 months, C4d deposition in peritubular capillaries, and the presence of anti-human leukocyte antigen antibodies. RESULTS: Six (11.3%) patients met the criteria of CAMR. MLPTC was the most sensitive (83.3%) and specific (89.1%) histological criterion (P=0.0008). Five patients had peritubular capillaritis at their 3-month biopsy. They all developed MLPTC at 1 year (P<0.0001). Three of the patients with early peritubular capillaritis met the criteria of CAMR at 1 year (P=0.0002). CONCLUSIONS: Through early detection of subclinical peritubular capillaritis, renal allograft recipients who are at risk for development of MLPTC might be identified. Larger series are needed to confirm these preliminary findings, but this report suggests peritubular capillaritis as an early detection marker for patients at risk for CAMR.