Abstract Background Although focused assessment with sonography for trauma (FAST) is considered to have high specificity, there are some case reports of false positives. This study aimed to investigate the characteristics of pediatric patients with blunt abdominal trauma and without intra‐abdominal injuries (IAI) among FAST‐positive patients. Methods This retrospective study was conducted on children less than 17 years old who visited the emergency department because of trauma and underwent FAST between April 2010 and March 2014. FAST‐positive children were categorized into groups with and without IAI and were subsequently compared. Results Ninety‐two patients (60 boys) with a median age of 7 years were included. Seventy‐six of them (82.6%) did not have IAI. The ratio of patients with abnormal abdominal surface findings, abdominal pain, and signs of peritoneal irritation was significantly lower in the group without IAI than in the group with IAI. The ratio of patients with ascites in the Morison and splenorenal pouches was lower in the group without IAI compared to the group with IAI (1% vs. 38%, p < 0.001; 3% vs. 19%, p = 0.030). Furthermore, the ratio of patients with ascites in the pelvic cavity was significantly higher in the group without IAI than in the group with IAI (92% vs. 75%, p = 0.0046; 91% vs. 50%, p < 0.001). Conclusions In this study, false‐positive FAST cases in pediatric patients with blunt abdominal trauma tend to lack abdominal findings. These results may provide important information when considering the outcomes of positive FAST results.