Objective To evaluate the dosimetric difference between volumetric modulated arc therapy (VMAT) plans with and without an interdigitating multileaf collimator (MLC) in the treatment of multiple brain metastases, and to investigate the advantages of MLC interdigitation in VMAT plans for multiple brain metastasis. Methods A retrospective study was performed on clinical data from 15 patients with multiple brain metastases in our hospital. A dual arc VMAT plan with an interdigitating MLC (VMAT-1) was designed on computed tomography (CT) images. Then, keeping all parameters unchanged, another VMAT plan with a non-interdigitating MLC (VMAT-2) was made after re-optimization. The conformity index (CI) and homogeneity index (HI) of the planning target volume (PTV), doses to organs at risk (OARs), monitor units (MUs), control points, delivery time, and planning time were compared between the two treatment plans using the Wilcoxon signed rank test. Results VMAT-1 achieved a better HI than VMAT-2(P=0.04), while there was no significant difference in CI between the two plans (P=0.33). VMAT-1 had a significantly higher D_98% for PTV than VMAT-2(P=0.04). Compared with VMAT-2, the D_mean to the brain stem in VMAT-1 was significantly reduced by 4%(P=0.04). The doses to other OARs in VMAT-1 were similar to those in VMAT-2. In some patients, compared with VMAT-2, VMAT-1 had a lower dose to normal tissue at the junction of neighboring CT planes of tumor. Compared with VMAT-2, the MUs of VMAT-1 were significantly increased by 4%(P=0.01), while there were no significant differences in control points or delivery time between the two plans (P=0.81, 0.73). VMAT-1 had the planning time significantly reduced by 26% compared with VMAT-2(P=0.00). Conclusions In VMAT plans for multiple brain metastases, MLC interdigitation could save the VMAT planning time and improve the planning efficiency.