Background The last major North American cooperative group clinical trial for relapsed favorable histology Wilms tumor (FHWT) was completed in 2002. The outcomes of patients with relapsed Wilms tumor subsequently treated outside of clinical trials is unknown. The aim of this study was to assess the efficacy and toxicity of salvage therapies used for patients with FHWT suffering first relapse. Methods We conducted a retrospective chart review of patients treated for first relapse of FHWT at six large North American institutions from January 2002 through August 2018. Results Ninety-four patients were identified. Thirty-six patients were classified as standard-risk relapse (SRR), 49 patients as high-risk relapse (HRR) and seven patients as very high-risk relapse (VHRR). Twenty-one patients with SRR were treated with Regimen I. The 4-year EFS and OS for SRR was 82.4% and 93.3%, respectively, with median follow up of 72 months. Twenty-eight HRR/VHRR patients were treated with ICE therapy while 13 received NWTS5 Stratum C. No patient completed protocol therapy per stratum C; median maintenance cycles administered was 2. The 4-year EFS and OS for HRR/VHRR was 32.6% and 58.3%, respectively, with median follow up of 33 months. Conclusions Outcomes for all strata of relapsed WT patients treated in a non-clinical setting appear to have similar outcomes as historical cohorts treated on NWTS5. Improved strategies are urgently needed for HRR and VHRR relapses.