Background: Some studies have indicated that a local injection of Botulinum Toxin Type A (BTX-A) is a promising therapy for trigeminal neuralgia (TN). However, BTX-A treatment is still ineffective for approximately 10-43% of patients. We therefore investigated which factors are associated with the therapeutic effect in BTX-A treatment of medically refractory, classical TN. Methods: We performed a retrospective cohort study with a total of 104 patients who were receiving BTX-A injection for medically refractory classical TN between August 2013 and October 2016. A VAS score, pain attack frequency per day as well as patients' overall response to treatment and side effects were evaluated in 104 patients with TN who were receiving BTX-A. Results: A total of 87 patients reported successful results; 41 stated that their pain was completely controlled while 46 reported adequate pain relief, totaling 83.7%. Our study suggests that treatment success was higher in patients 50 or older (OR=3.66, 95% CI: 1.231-10.885). Univariate and multivariate analyses demonstrated that the patient's age was independently associated with treatment outcome (OR=1.72, 95% CI: 1.063-2.282), with >= 50 years being a significant predictor of pain relief (P=0.020 and P=0.033, respectively). Seventeen patients (16.3%) reported mild side effects. Conclusion: A local injection of BTX-A may be a safe and efficient treatment for classical TN which lasts for several months. BTX-A is a novel strategy which is particularly worth trying for particularly middle-aged and elderly patients who cannot tolerate drug side effects and may be afraid of serious complications from microvascular decompression.