The undescended testis (cryptorchidism) is the most common correctable disorder in paediatric urology (1-4.6% of newborns). An important role of the scrotum is to keep the temperature of the testes 2-40C below core body temperature. Here, Shiraishi et al. from Japan have studied testicular volume (using ultrasonography) and temperature (using a CoreTemp device) prior to, and one year following orchidopexy. Overall, 82 children with unilateral palpable cryptorchidism and 24 children with unilateral impalpable testes were evaluated. For palpable testes, significant differences were found between preoperative and one-year postoperative mean volumes in both the undescended and descended sides. Preoperative temperature of the extrainguinal testes were significantly higher than that of controls (35.60C vs. 34.40C). Significant decreases in testicular temperature were noted after orchidopexy in both high scrotal and extrainguinal cryptorchidism. With regards non-palpable testes, a significant difference in testicular volume was noted between undescended and descended testes. The testicular temperature one year following laparoscopic staged Fowler-Stephens orchidopexy (LSFSO) remained significantly higher on the undescended side than on the descended side (34.70C vs. 33.90C). Interestingly, they showed that a transinguinal route for the mobilised testis appeared to provide a better testicular temperature (34.40C vs. 35.30C) than utilising the ‘Prentiss manoeuvre’ (rerouting of the testis medial to the inferior epigastric vessels). The manuscript shows for the first time that a decrease in testicular temperature after orchidopexy is associated with an increase in testicular volume. I am unable to explain the differences found regarding the temperature differences demonstrated in relation to LSFSO; both transinguinal routing or undertaking of a Prentiss manoeuvre should place the testis in the scrotum (i.e. there should be no difference in testicular temperature in the long term). However, it may relate to technical differences in surgery e.g. sacrifice or preservation of the gubernaculum, which could affect counter current heat exchange mechanisms and hence heat clearance. Should these differences bear out in future studies, it might suggest modifying surgical techniques may be of benefit (improved testicular volume and spermatogenesis).