Background: This study aims to determine whether 3 sessions per week of acupuncture treatment is superior to 1 session per week of acupuncture treatment for symptomatic outcomes in knee osteoarthritis. Methods/design: This is a two parallel-group, assessor-blinded, randomized controlled trial. Sixty patients with knee osteoarthritis (Kellgren-Lawrence grade II or III) will be recruited and randomly allocated to receive 24 or 8 sessions (group M or group L) of acupuncture treatment in a 1:1 ratio. Patients in group M will receive 3 sessions per week of acupuncture for 8weeks. Patients in group L will receive acupuncture once per week for 8weeks. The primary outcome is the response rate-the percentage of patients achieving a decrease >= 2 points on a numerical rating pain scale anda decrease >= 6 points in the Western Ontario and McMaster Universities Osteoarthritis Index function score at 8weeks compared with baseline. Secondary outcomes include pain, function, overall effect, quality of life, and treatment credibility and expectancy. Discussion: Three sessions per week of acupuncture treatment may be superior to 1 session per week of acupuncture treatment for symptomatic outcomes in knee osteoarthritis. Results of the study will be of great importance for the guidelines of clinical therapy.