BACKGROUND: Surgical repair of inguinal hernia is one of the most common day case surgeries in the pediatric population. This study compared the postoperative analgesic effects of transversalis fascia plane block (TFB) versus quadratus lumborum block (QLB) in children scheduled for open unilateral inguinal herniotomy. METHODS: In this prospective, randomized, double-blind, controlled non-inferiority study, 76 eligible patients were recruited. Patients were randomly allocated to either the TFB or QLB group. The primary outcome measure was the proportion of patients who needed rescue analgesia during the first postoperative 12 h. The secondary outcomes were, the time needed to perform the block, the postoperative FLACC score, intraoperative heart rate (HR) and mean arterial pressure (MAP). RESULTS: The proportion of patients who required a rescue analgesic was comparable (p = 1.000) between the TFB group (7/34, 20.5%) and the QLB group (6/34, 17.6%). The median [Q1-Q3] time needed to perform the block (min) was significantly longer (p < 0.001) in the QLB group (5[5]) compared with the TFB group. The postoperative FLACC pain scale was comparable between the two groups at all-time points of assessment. There is no difference regarding the heart rate and mean arterial blood pressure values at the time points that the values were recorded. (P > 0.005). CONCLUSIONS: Both TFB and QLB similarly provide good postoperative analgesia by reducing the proportion of patients who required rescue analgesia, pain scores and analgesic consumption. Moreover, TFB is technically easier than QLB.