BACKGROUND: Although botulinum toxin type A (BTX-A) injection has been proved to reduce topical sebum secretion, the impact of intradermal BTX-A injection on scalp sebum production has never been reported. OBJECTIVES: The purpose of this study was to investigate the efficacy and safety of intradermal BTX-A treatment vs intradermal normal saline (NS) injection for scalp sebum secretion regulation. METHODS: This multicenter, randomized, double-blinded, prospective study recruited patients complaining of oily scalp and/or hair. The patients were randomly allocated to receive either 1 session of intradermal BTX-A or NS injection. The baseline and posttreatment scalp sebum secretion at 24, 48, 72, and 96 hours postshampooing was measured with a Sebumeter SM815 (Cutometer Dual MPA 580, Courage & Khazaka, Cologne, Germany) at 1, 3, 4, and 6 months after treatment. The patients' comments, satisfaction, and adverse events were evaluated and compared. RESULTS: In total, 25 patients in the BTX-A group and 24 patients in the NS group completed the follow-up. For the treated region, compared with NS, intradermal BTX-A treatment (50-65 U) significantly reduced scalp sebum secretion at 24, 48, and 72 hours postshampooing at the 1- and 3-month follow-up visits (P < 0.05). No significant difference between the 2 groups was observed at 4 and 6 months after the treatment. The patients' satisfaction ratings were significantly higher for the BTX-A treatment (P = 0.000). No serious adverse events occurred. CONCLUSIONS: Compared with NS, 1 session of intradermal BTX-A injection (50-65 U) effectively and safely reduced scalp sebum secretion and greasiness perception in the treated region at 24 and 48 hours postshampooing for 3 months.