Glioblastomas (GBMs) are the most malignant and intractable of all cancers, with an unfavourable clinical prognosis for affected patients. The objective was analysis the sensitivity of GBM cells to the antimicrobial peptides (AMPs) cathelicidin (LL-37) and protegrin-1 (PG-1), both alone and in combination with chemotherapy, to predict overall survival (OS) in the patients. The study was conducted on 27 GBM patients treated in the neurosurgical departments of the Almazov Medical Research Centre (Saint-Petersburg, Russia) from 2021 to 2024. The cytotoxic effects of chemo-therapy, AMPs and their combinations on brain tumor cells were assessed by MTT assay using 50%-inhibitory concentration (IC50). In GBM cells from the patients, LL-37 and PG-1 exhibited strong anticancer effects, surpassing those of chemotherapy drugs. These LL-37 and PG-1 anti-cancer effects were associated with a statistically significant increase in life expectancy and OS in GBM patients. These findings were confirmed by the experiments on rats with C6 glioma, where intranasal administration of LL-37 (300 μM) and PG-1 (600 μM) increased the life expectancy of the animals to 69 and 55 days, respectively, compared to 24 days in the control group (HR=4.139, p=0.0005; HR=2.542, p=0.0759). Additionally, the combination of LL-37 and PG-1 with chemo-therapy drugs showed that a high IC50 of LL-37 with cisplatin (cutoff >800 μM) in GBM cells was associated with increased life expectancy (19 vs 5 months, HR=4.708, p=0.0101) and OS in GBM patients. These combinations could be used in future GBM treatments.