Non-operative treatment of uncomplicated appendicitis in children is gaining ground. Pending definitive evidence regarding its effectiveness, there is a call to evaluate clinical recovery after non-operative treatment. In this study, we analyzed data collected during initial admission of a multicenter prospective cohort in which children, 7–17 year, were treated non-operatively for uncomplicated appendicitis. During admission clinical parameters (pain and gastro-intestinal symptoms), inflammation parameters and sequential abdominal ultrasound were recorded. In total, 45 children were included, 42(93%) were discharged without the need for appendectomy; median [IQR] pain scores on admission were 5 [4–7], decreasing to 2 [0–3] after 1 day of treatment. Initially, 28/42 (67%) reported nausea and 19/42 (45%) vomiting; after 1 day, this was 3/42 (7%) and 1/42 (2%), respectively. White blood cell count declined from a median [IQR] of 12.9 [10.7–16.7] 10E9/L on admission to 7.0 [5.8–9.9] 10E9/L on day 1. Median [IQR] C-reactive protein levels increased from 27.5 [9–69] mg/L on admission to 48 [22–80] mg/L on day 1, declining to 21.5 [11–42] mg/L on day 2. Follow-up ultrasound showed no signs of complicated appendicitis in any of the patients. Conclusion: Clinical symptoms resolved in most children after 1 day of non-operative treatment. This suggests that non-operative treatment is a viable alternative to appendectomy regarding clinical recovery. Trail registration: NCT01356641What is Known:• Non-operative treatment of uncomplicated appendicitis in children is safe and its use around the world is gaining ground, however high quality evidence from adequately designed randomized trials is still lacking.• Concerns have been raised regarding the potentially prolonged clinical recovery associated with non-operative treatment.What is New:• Most clinical symptoms resolve after 1 day of non-operative treatment in the majority of children.