The LyKID study is a nationwide survey in France of lymphoma patients with renal involvement based on biopsy and/or imaging, to evaluate its impact on disease outcome and renal function. A total of 87 adult cases of B or T-cell lymphomas were retrospectively analyzed. Interstitial topography was observed in most of the kidney biopsies (54/66; 80%). Kidney failure (glomerular filtration rate <60 mL/min/1.73 m ² ) was present in 47% of patients and was associated with non-significantly different outcome. After lymphoma treatment, 44% of patients had persistent chronic kidney failure (CKF); kidney failure at diagnosis was the only parameter associated with CKF in multivariate analysis. DLBCL (diffuse large B-cell lymphomas) represented half of the series, with noticeably CNS (central neurological system) relapse in 17% patients, while fewer than one of two patients had received CNS prophylaxis. To our knowledge, the LyKID study represents the largest published non-autopsy lymphoma series with renal involvement.