BACKGROUND:The incidence of nonrevision reoperations after anterior cruciate ligament reconstruction (ACLR) is less commonly studied and quantified. PURPOSE:To describe the incidence of short-term reoperations after primary ACLR for the 4 most common procedures and to evaluate the risk factors associated with these reoperations. STUDY DESIGN:Case-control study; Level of evidence, 3. METHODS:Patients who underwent ACLRs and were enrolled in an ACLR registry between February 2005 and September 2011 were evaluated. First reoperations after primary ACLR performed for the 4 most common procedures (meniscal procedures, cartilage procedures, hardware removal procedures, and arthrofibrosis procedures) were the primary end points of the study. Patient, surgical, surgeon, and hospital risk factors associated with reoperations were evaluated, and Cox regression models were employed. Hazard ratios (HRs) and 95% confidence intervals (CIs) are reported. RESULTS:A total of 14,522 ACLRs were identified. The patients had a mean age of 29.4 ± 11.5 years and were mostly male (63.3%) and white (48.3%). The mean follow-up was 1.9 ± 1.5 years (range, 0-6.7 years), and the median time to reoperation was 301 days (interquartile range, 172-515 days). The reoperation rate per 100 person-years of follow-up was 1.1 for meniscal reoperations, 0.3 for cartilage reoperations, 0.4 for hardware removal reoperations, and 0.4 for arthrofibrosis reoperations. Meniscal repair at the index ACLR was a significant risk factor for subsequent meniscal procedures (HR, 4.19; 95% CI, 3.10-5.67). Sports medicine fellowship training of the surgeon (HR, 2.17; 95% CI, 1.01-4.62) and older patient age (≤17 vs ≥26 years) (HR, 0.32; 95% CI, 0.12-0.81) were significant risk factors for cartilage reoperations. Use of allografts (HR, 1.90; 95% CI, 1.10-3.30) and female sex (HR, 1.75; 95% CI, 1.16-2.64) were risk factors for hardware removal reoperations. Female sex (HR, 2.48; 95% CI, 1.66-3.71) and prior surgery (HR, 3.02; 95% CI, 1.39-6.53) were risk factors for subsequent surgery for arthrofibrosis. CONCLUSION:Overall short-term reoperation rates after ACLR are relatively low. Risk factors for subsequent surgery vary depending on the type of surgery evaluated. Some of the risk factors observed for reoperations include previous meniscal repair, female sex, allografts, prior surgery, older patient age, and being operated on by a sports medicine fellowship-trained surgeon.