Purpose: To assess liver remnant volume regeneration and maintenance, and complications in the long-time follow-up of donors after living donor liver transplantation using CT and MRI. Materials and Methods: 47 donors with a mean age of 33.5 years who donated liver tissue for transplantation and who were available for follow-up imaging were included in this retrospective study. Contrast-enhanced CT and MR studies were acquired for routine follow-up.?Two observers evaluated pre- and postoperative images regarding anatomy and pathological findings. Volumes were manually measured on contrast-enhanced images in the portal venous phase, and potential postoperative complications were documented. Pre- and postoperative liver volumes were compared for evaluating liver remnant regeneration. Results: 47 preoperative and 89 follow-up studies covered a period of 22.4 months (range: 1???84). After right liver lobe (RLL) donation, the mean liver remnant volume was 522.0?ml (??144.0; 36.1?%; n?=?18), after left lateral section (LLS) donation 1,121.7?ml (??212.8; 79.9?%; n?=?24), and after left liver lobe (LLL) donation 1,181.5?ml (??279.5; 72.0?%; n?=?5). Twelve months after donation, the liver remnant volume were 87.3?% (RLL; ??11.8; n?=?11), 95.0?% (LS; ??11.6; n?=?18), and 80.1?% (LLL; ??2.0; n?=?2 LLL) of the preoperative total liver volume. Rapid initial regeneration and maintenance at 80?% of the preoperative liver volume were observed over the total follow-up period.?Minor postoperative complications were found early in 4 patients. No severe or late complications or mortality occurred. Conclusion: Rapid regeneration of liver remnant volumes in all donors and volume maintenance over the long-term follow-up period of up to 84 months without severe or late complications are important observations for assessing the safety of LDLT donors. Key Points: Liver remnant volumes of LDLT donors rapidly regenerated after donation and volumes were maintained over the long-term follow-up period of up to 84 months without severe or late complications. Citation Format: ??Klink T, Simon P, Knopp C et?al. Liver Remnant Regeneration in Donors After Living Donor Liver Transplantation: Long-Term Follow-Up Using CT and MR Imaging. Fortschr R?ntgenstr 2014; 186: 598???605