To evaluate the efficacy and toxicity of intravitreal carboplatin plus melphalan for the treatment of vitreous seeds in eyes with retinoblastoma (RB). This retrospective series at a tertiary referral center included 22 consecutive RB patients who had received intravitreal carboplatin (16μg per 0.05ml) combined with melphalan (30μg in 0.03ml) [IVi (Ca-Me)] for treatment of vitreous seeds. Tumor control and drug toxicities were recorded. There were 22 eyes of 22 patients, divided into primary group (n = 13) without history of previous intravitreal chemotherapy (IViC) and refractory group (n = 9) with history of previous IViC using melphalan and/or topotecan. The demographics and clinical findings of the primary and refractory groups did not differ significantly. The 6-month follow-up revealed complete vitreous seed control (77% vs. 89%, p = 0.47). Vitreous seed recurrence was detected in 1 eye of each group at 6months. During the next 18-month follow-up period, no recurrence of seed was observed. The response to IVi (Ca-Me) was not significantly influenced by previous IViC (p = 0.70), primary systemic or intra-arterial chemotherapy (p = 0.45), or the type of regression (p = 0.35). The most common tumor treatment complications were retinal detachment (RD) (n = 2), early hypotony (n = 2) and late hypotony (n = 4, unrelated), cataract (n = 2), and severe pigment dispersion (n = 1). Enucleation was performed in 8 eyes, for total RD (n = 1), phthisis bulbi (n = 5), and extensive solid tumor recurrence (n = 2). There was no case of orbital invasion, systemic metastasis, or death. Based on this interventional case series for primary and refractory vitreous RB seeds, carboplatin plus melphalan therapy may be effective with few toxic side effects.