Objectives: To determine whether the preoperative and intraoperative findings at unilateral microsurgical subinguinal varicocelectomy are predictive of semen analysis changes postoperatively. Methods: We identified 42 men who had undergone left-sided microsurgical subinguinal varicocelectomy at our institution and had at least one semen analysis before and after surgery. The preoperative varicocele grade and number and size of spermatic cord veins ligated were recorded. The veins were defined as small (less than 1.0 mm), medium (1.0 to 3.9 mm), and large (4.0 mm or larger). The generalized estimating equation approach was used to assess whether patient age, varicocele grade, number of small, medium, or large veins ligated, total number of veins ligated, and net diameter of all veins ligated were predictive of repeated measurements of semen analysis outcomes. Results: Increasing patient age was associated with a slight decline in sperm concentration (P = 0.046). The number of veins ligated correlated positively with an increase in total motility (P = 0.017). The repair of grade II varicoceles was associated with a significantly greater increase in normal morphology than did the repair of grade I or III varicoceles (P = 0.004). None of the other variables examined were predictive of semen analysis outcome (P >0.05). Conclusions: The relationship between the preoperative/intraoperative findings and semen analysis outcomes after microsurgical subinguinal varicocelectomy remains unclear.