Neck pain is common; it can limit a person's ability to participate in normal activities and is costly. Exercise therapy is a widely used treatment for neck pain. This review includes active exercises (including specific neck and shoulder exercises, stretching, strengthening, postural, functional, eye-fixation, and proprioception exercises) prescribed or performed in the treatment of neck pain. Studies in which exercise therapy was given as part of a multidisciplinary treatment, multimodal treatment (along with other treatments such as manipulation or ultrasound), or exercises requiring application by a trained individual (such as hold-relax techniques, rhythmic stabilization, and passive techniques) were excluded. Twenty-one trials were used to assess if exercise could help reduce neck pain; improve function, patient satisfaction and/or quality of life. In these trials exercise was compared to either a placebo treatment, or no treatment (waiting list), or exercise combined with another intervention was compared with that same intervention (which could include manipulation, education/advice, acupuncture, massage, heat or medications). Results showed that exercise is safe, with temporary and benign side effects, although almost half of the trials did not report on adverse effects. An exercise classification system was used to ensure similarity between protocols when looking at the effects of different types of exercises. Exercise did show an advantage over the other comparison groups. There appears to be a role for exercises in the treatment of chronic neck pain and cervicogenic headache if stretching and strengthening exercises are focused on the neck and shoulder blade region. There appears to be no advantage to arm stretching and strengthening exercises or a general exercise program. There were a number of challenges with this review; for example, the number of participants in most trials was small and there was limited evidence on optimum doseage requirements.