The occurrence of headache as a sequela of low back pain was examined in a sample of chronic pain patients. All patients had low back pain without history of head, neck, or upper back injury or headache onset simultaneous with the low back pain, Consistent with prior research, headache was found to be a common concomitant of back pain. In many patients, headache was found to have begun or exacerbated markedly after onset of low back pain. Prevalence of migraine in female patients was significantly higher than the population prevalence for females in the United States; this was not true for male patients. Potential mechanisms for explaining the high prevalence of migraine following low back pain are discussed, including increased muscle tension, psychosocial factors, and analgesic overuse.