Asymptomatic contralateral inguinal hernias are often present during initial inguinal hernia repair. Data on long-term results and progression to symptomaticity are sparse. The purpose of this study was to assess long-term rates and risk factors for contralateral inguinal hernia repair following unilateral inguinal hernia repair. Using New York Statewide Planning and Research Collaborative administrative data, 32,384 adults who underwent initial inguinal hernia repair during 2002–2003 in New York State and achieved 10-year follow-up were identified. ICD-9 and CPT codes were used to identify patients. Patients were followed for 10 years subsequent to their operation to assess for contralateral repair. Those who did not achieve 10-year follow-up were excluded. Risk factors were compared using descriptive univariate statistics. Significant variables were then analyzed via multivariate regression models. For adult patients having primary unilateral hernia repair, 3364 patients (6.73 %) had contralateral repair during the follow-up period. After excluding “loss of follow-up” patients, the contralateral repair rate was 10.8 %. Contralateral hernia repairs first occurred at a mean of 3.9 ± 3.5 years and a median of 2.5 years after the initial surgery. Risk factors included age >45 years (OR 1.7 [1.4–2.0], p < 0.001), male gender (OR 2.2 [1.9–2.6], p < 0.0001), and white race (OR 1.6 [1.1–2.4], p < 0.001). Factors associated with decreased likelihood for repair included: congestive heart failure (OR 0.6 [0.4–0.9], p = 0.01), diabetes (OR 0.7 [0.5–0.8], p = 0.02), neurological disorders (OR 0.6 [0.4–0.9], p = 0.02), obesity (OR 0.3 [0.1–0.8], p = 0.01), and alcohol abuse (OR 0.2 [0.03–0.8], p = 0.03). The 10-year probability of necessitating a contralateral inguinal hernia repair is significant. Elderly white males were more likely to undergo repair. Those less likely to undergo repair had significant comorbid conditions, possibly due to their poor suitability for intervention. These data highlight a key benefit of the laparoscopic approach over open repairs. Based on these data, an argument for laparoscopy with routine contralateral inspection in higher-risk patients can be made.