A clinical study tested the therapeutic efficacy of Botulinum toxin A (BTXA) when injected into symptomatic neck muscles after one injection session. Patients with chronic neck pain were randomly assigned to receive either a high dose of an active treatment or an injection of the same volume of normal saline. Patients were compared for 4 months using a comprehensive set of outcome measures that included the Neck Pain and Disability Scale (Spine 24 (1999) 1290) and pressure algometry (Arch Phys Med Rehabil 67 (1986) 406; Pain 30 (1987) 115; Clin J Pain 2 (1987) 207). Analyses were consistent in showing significant benefits from the injection session; however, the effects were not specific to the group treated with BTXA. Both treatment and control groups showed a significant decline in pain and disability across time and an increased ability to withstand pressure on trigger points. The heavy incidence of adverse events in the treatment group may partly explain the absence of a treatment effect specific to BTXA. The results show that a single dose treatment without physical therapy is not effective for chronic neck pain.