Objectives To correlate the varicocele grade on physical examination with the number and size of the veins present and ligated during surgery. Varicoceles are correctable causes of male factor infertility. No prior anatomic studies have correlated the preoperative clinical grade of a varicocele with the number of veins discovered and ligated during microsurgical subinguinal repair. Methods A total of 65 consecutive men (mean age 33.8 years) diagnosed during office evaluation with either unilateral left varicocele or bilateral varicoceles underwent microsurgical subinguinal varicocelectomy by one urologist. At surgery, the number and size (small, less than 1.0 mm; medium, 1.0 mm or greater to less than 4.0 mm; large, 4.0 mm or greater) of the spermatic cord veins present and ligated were recorded. These findings were correlated with the size of the preoperative varicocele grade. Results Of the 71 varicocele units, 65 qualified for analysis. Of the patients with a grade 1 varicocele, a mean (±SD) of 2.4 (±2.5) small veins, 4.7 (±2.1) medium veins, 0.3 (±0.58) large veins, and 7.5 (±3.0) total veins were ligated. Of patients with a grade 2 varicocele, a mean of 2.6 (±2.3) small veins, 5.3 (±3.1) medium veins, 0.47 (±0.78) large veins, and 8.3 (±3.2) total veins were ligated. Of patients with grade 3 varicoceles, a mean of 1.8 (±1.8) small veins, 4.6 (±2.3) medium veins, 1.0 (±0.75) large veins, and 6.9 (±2.6) total veins were ligated. Using analysis of variance, the grade 3 varicoceles had significantly more large veins than did grade 1 varicoceles (P <0.05). Conclusions Grade 3 varicoceles have a greater number of large veins compared with grade 1 varicoceles.