The purposes of this multi-center study were: (a) to document the location and type of meniscal and chondral lesions that accompany anterior cruciate ligament (ACL) tears, and (b) to test for possible relationships between these lesions and patient age, time from initial injury (TFI), and sports level (i.e., recreation, amateur, professional, and national). The cases of 764 patients with ACL tears who underwent arthroscopy for the first time were retrospectively analyzed. The group included 684 males and 80 females of mean age 27 years (range 14-59 years). The mean TFI was 19.8 months (range 0.2-360 months). Eighty-seven percent of the group engaged in regular sporting activity. Thirty-seven percent had medial meniscal tears, 16% had lateral meniscal tears, and 20% had tears of both menisci. The most common tear types were longitudinal tears in the posterior and middle horns of both menisci. Tears of the lateral meniscus were more centrally located than those of the medial meniscus. Incomplete tears and radial tears were significantly more common in the lateral meniscus. Nineteen percent of the knees had one or more chondral lesions. Sixty percent of the chondral lesions were located in the medial tibio-femoral compartment. Patient age was statistically associated with presence of a medial meniscal tear, presence of a grade 3 or 4 chondral lesion, and presence of a complex tear of the medial meniscus. Sports level was not statistically related to any of the parameters studied. The odds of having a medial meniscal tear at 2 to 5 years TFI were 2.2 times higher than the odds in the first year post-injury, and the odds at >5 years were 5.9 times higher than at 0 to 12 months TFI. The frequency of lateral meniscal tear remained fairly constant at 2 years TFI. The odds of having a grade 3 or 4 chondral lesion were 2.7 times greater at 2 to 5 years TFI than they were at I year post-injury, and these odds increased to 4.7 when patients at >5 years TFI were compared to those in the 2 to 5 years category. Multivariate analysis demonstrated that TFI and age were equally important predictors of lateral meniscal tears and of grade 3 or 4 chondral lesions; however, TFI was the better predictor of medial meniscal tear.