Objective. The purpose of this study was to investigate whether there is an association between communicating congenital hydroceles and testicular volume in children. Methods. Seventeen children with unilateral communicating congenital hydroceles who underwent hydrocelectomies were included in the study. Testicular volumes were measured before and after hydrocelectomy on both the affected and unaffected sides. Results. We found statistically significant differences in testicular volumes between the normal sides (mean +/- SD, 0.62 +/- 0.24 mL) and the sides with hydroceles (0.72 +/- 0.26 mL) before surgery (P <.001) and in testicular volumes of the sides with hydroceles before (0.72 +/- 0.26 mL) and after (0.60 +/- 0.19 mL) surgery (P <.001). There was no significant difference in testicular volumes before (0.62 +/- 0.24 mL) and after (0.62 +/- 0.21) surgery on the normal sides (P =.978). The mean decrease in volume of the testes with hydroceles after hydrocelectomy was approximately 15%. Conclusions. This study shows that there is an association between congenital communicating hydroceles and testicular volume in children. Clinicians should be aware that there is a decrease in testicular volume after hydrocelectomy so they do not misdiagnose this change as postoperative trauma or atrophy.