Importance Previous studies on mesh weights have focused on the definitions of lightweight and heavyweight meshes, which were not based on clinical outcomes. Objective To investigate which mesh weight would be associated with the lowest reoperation rate for recurrence in laparoscopic inguinal hernia repair. Design, Setting, and Participants This nationwide cohort study was based on prospectively collected data on eligible patients aged 18 years or older who had undergone a primary transabdominal preperitoneal laparoscopic inguinal hernia repair in Denmark between January 1998 and July 2023 from the Danish Inguinal Hernia Database, obtained through population-based sampling. The final grouping included patients who received a mesh with a weight of <45 g/m 2 , 45-65 g/m 2 , or >65 g/m 2 . The database linkage to the Danish National Patient Registry made it possible to follow-up patients until the date of data extraction, death, emigration, or reoperation. Sequential explorative analyses were conducted to compare all mesh weight intervals to find the weight interval that resulted in the lowest risk of reoperation for recurrence. Main Outcomes and Measures The main outcome was reoperation for recurrence using a Cox proportional hazards regression model. Results A total of 43 986 inguinal hernias from 36 446 patients were included: 16 949 in the less than 45-g/m 2 group, 16 531 in the 45- to 65-g/m 2 group, and 10 506 in the greater than 65-g/m 2 group. A total of 1910 (4.34%) inguinal hernias underwent reoperation for recurrence. The mesh weight interval of 45 to 65 g/m 2 had the lowest risk of reoperation for recurrence. Compared with a mesh weight of 45 to 65 g/m 2 , a mesh weight of less than 45 g/m 2 had a hazard ratio for reoperation of 2.6 (95% CI, 2.2-2.8; P < .001), and a mesh weight of greater than 65 g/m 2 had a hazard ratio of 2.4 (95% CI, 2.1-2.8; P < .001) for reoperation. Conclusions and Relevance This nationwide cohort study found that a mesh weight of 45 to 60 g/m 2 resulted in the lowest risk of reoperation for recurrence compared with other mesh weights in laparoscopic inguinal hernia repair. These findings suggest that selecting a mesh within 45 to 60 g/m 2 can optimize outcomes and reduce the need for reoperation.