OBJECTIVE Short-course radiotherapy (25 Gy in 5 fractions) has been shown to be non-inferior to standard course radiotherapy in elderly and frail patients (60 Gy in 30 fractions). The purpose of this study was to determine the effects of temozolomide combined with short-course radiotherapy on the outcome of elderly and frail patients. METHODS Between January 2017 and November 2018, 90 patients (65 years old and KPS score of 50-70; 65 years old and KPS score of 80-100; and 65 years old and KPS score of 50-70) were assessed for eligibility. Nine patients were excluded because they did not meet the inclusion criteria, six patients declined to participate, and four patients were unable to complete the quality-of-life questionnaire. The remaining 71 patients were divided into two arms at random in a 1:1 ratio. Short-course radiotherapy with concurrent temozolomide and adjuvant temozolomide was given to Arm 1, while short-course radiotherapy alone was given to Arm 2. RESULTS In terms of overall survival and progression-free survival, radiotherapy with concurrent temozolomide and adjuvant temozolomide outperformed short-course radiotherapy alone. The median overall survival in arm 1 was 146 days and 121 days in arm 2 (P=0.146). The median progression-free survival in arm 1 was 109.50 days, while it was 77 days in arm 2 (P=0.028). With a median follow-up time of 6 months, the quality of life at 4 weeks and 12 weeks after treatment was not different between the two arms. CONCLUSIONS We concluded that adding temozolomide to short-course radiotherapy significantly improved progression-free survival and showed an increasing trend in overall survival without compromising the quality of life.