Diagnostic cervical medial branch blocks and zygapophysial joint blocks were used to test the hypothesis that the cervical zygapophyseal joints can be the source of pain in patients with idiopathic neck pain. Complete temporary relief of all symptoms was obtained in 17 out of 24 consecutive patients. Two major groups of patients were those with neck pain and headache stemming from the C2-3 joints, and those with neck pain and shoulder pain stemming from the C5-6 joints. Internal-control observations in nine of the 17 patients established the diagnostic validity of the blocks used. The high yield of positive responders in this study probably reflects the propensity of patients with zygapophysial joint syndromes to gravitate to a pain clinic when this condition is not recognised in conventional clinical practice.