There is a paucity of data regarding patterns of progression in children with high-grade glioma (HGG) or diffuse intrinsic pontine glioma (DIPG) treated with bevacizumab (BVZ) at diagnosis. We performed a retrospective study of 20 children with HGG or DIPG who received BVZ-based therapy at diagnosis on, or according to, a bi-institutional study. Magnetic resonance imaging (MRI) characteristics of first and most recent progressions were reviewed. Comparison was made to a control group of 19 patients who never received BVZ. Imaging definitions of progressive disease (PD) were local: at primary site or within 2 cm, contiguous; diffuse: >2 cm away but contiguous with primary site, ill-defined and infiltrative; distant: new, non-contiguous disease. In the BVZ-treated group, 14 patients had DIPG, six patients had HGG. Median age was 7 years (range: 3-21). Median time to PD and follow-up were 8.8 months (range 4-21) and 11 months (range: 6-25), respectively. Among 14 patients with PD, 8 (57.1 %) had local PD, 6 (42.9 %) had local and diffuse/distant PD, at initial progression. At most recent progression, a median of 10.8 months (range 6-25) from diagnosis, 10 of 14 (71.4 %) had at least diffuse (n = 8), or distant (n = 6) PD. In the comparable control group, 15 patients had PD: 11(73.3 %) local, 4 (26.7 %) local and diffuse/distant PD at first and most recent progressions. Based on these data, we postulate that BVZ may lead to a higher incidence of distant and diffuse disease in newly-diagnosed children with HGG or DIPG who received BVZ-based therapy.