This study investigates the association between socio-economic deprivation and tuberculosis (TB) treatment delays in England, 2000-2005. Patients reported to the Enhanced TB Surveillance system were assigned a deprivation score based on residential postcode, and categorized into deprivation quartiles. Data were analysed using Cox regression. The median interval from symptom onset to treatment initiation was 67 days (inter-quartile range 30-131). The effect of deprivation on this interval was modified by ethnic group and place of birth/time since entry into the United Kingdom. Longer intervals were experienced by the most deprived black Africans, Indians/Pakistanis/Bangladeshis and recent entrants to the United Kingdom, compared to the least deprived. In contrast, among white and UK-born patients, longer intervals were experienced by the least deprived. In conclusion, the effect of deprivation on TB treatment delays varies in different population groups. Efforts are needed to reduce delays including improving awareness of TB and increasing the index of clinical suspicion.