On the basis of National Comprehensive Cancer Network guidelines, clinical stage (CS) II seminoma is treated with radiotherapy or chemotherapy. Primary retroperitoneal lymph node dissection (RPLND) demonstrated recent success as first-line therapy for RP-only disease. Our aim was to confirm surgical efficacy and evaluate recurrences after primary RPLND for CS IIA/IIB seminoma to determine if various clinical factors could predict recurrences. Patients who underwent primary RPLND for seminoma from 2014 to 2021 were identified. All patients had at least 6 months of follow-up. Nineteen patients were part of a clinical trial. Patients receiving adjuvant chemotherapy were excluded from Kaplan-Meier recurrence-free survival (RFS) analysis. We identified 67 patients who underwent RPLND for RP-only seminoma. One patient had pN0 disease. Median follow-up time after RPLND was 22.4 months (interquartile range, 12.3-36.1 months) and 11 patients were found to have a recurrence. The 2-year RFS for RPLND-only patients without adjuvant chemotherapy was 80.2%. Patients who developed RP disease for a period > 12 months had the lowest chance of recurrence, with a 2-year RFS of 92.2%. Seven initial CS II patients were on surveillance for 3-12 months before surgery and no patients experienced recurrence. Pathologic nodal stage and high-risk factors such as tumor size > 4 cm or rete testis invasion of the orchiectomy specimen did not affect recurrence. CS II seminoma can be treated with surgery to avoid rigors of chemotherapy or radiotherapy. Patients with delayed development of CS II disease (> 12 months) had the best surgical results. Patients may present with borderline CS II disease, and careful surveillance may avoid overtreatment. Further study on patient selection and extent of dissection remains uncertain and warrants further investigation.