Purpose The aim was to evaluate the total diagnostic interval (TDI) and presenting complaints in children with brain tumours in Serbia. Methods This study retrospectively analysed 212 children aged 0–18 years newly diagnosed with brain tumours in two tertiary centres from mid-March 2015 to mid-March 2020 covering virtually all children with brain tumours in Serbia. TDI was calculated as the difference between the date of diagnosis and the date of symptom onset presented as a median in weeks. This variable has been evaluable for 184 patients. Results Overall TDI was 6 weeks. TDI was significantly longer in patients with low-grade tumours (11 weeks) than in patients with high-grade tumours (4 weeks). Children with the most frequent complaints (headache, nausea/vomiting and gait disturbance) were more likely to be diagnosed sooner. Patients with a single complaint had significantly longer TDI (12.5 weeks) contrasted to patients with multiple complaints (5 weeks). Conclusion TDI with a median of 6 weeks is similar to other developed countries. Our study supports the view that low-grade tumours will present later than high-grade tumours. Children with the commonest complaints and children with multiple complaints were more likely to be diagnosed sooner.