Background: Tuberculosis (TB) is a major public health problem in the Horn of Africa, with Ethiopia being the most affected where TB is increasing at a rate of 2.6% each year. The main contributing factor for this rise is increasing transmission due to large number of contagious patients, serving as reservoirs of infection within the community. Reduction of the time between onset of TB symptoms to diagnosis is therefore a prerequisite to bring the TB epidemic under control. The aim of this study was to measure the delay of TB patients in diagnosis and determine socio-cultural factors underlying the delay among pastoralist TB patients at TB management units in Somali Regional State (SRS) of Ethiopia.Methodology: A retrospective cross sectional study of 226 TB patients with pastoralist identity, was conducted in SRS of Ethiopia from June to September 2007. Time between onset of TB symptoms and first visit to professional health provider (patient delay), and the time between first visit to professional health provider to the date of diagnosis (medical provider’s delay) were analyzed. Besides, migration pattern and health seeking behaviour of pastoralists were qualitatively investigated using participatory rural appraisal (PRA) and informal interview techniques. The impact of these factors on the delay of TB patients in diagnosis was analysed.Result: A total of 226 pastoralist TB patients were included in this study, 93 (41.2%) were nomadic pastoralists and 133 (58.8%) were agro-pastoralists. Median patient delay was found to be 60 days, ranging 10-1800 days (83 days for nomadic pastoralists and 57 days for agro-pastoralists). Median health provider’s delay was 6 days and median total delay was 70 days in this study. Patient delay constituted 86% of the total delay. Lack of access to health care which is further complicated by seasonal migration of pastoralists, and low biomedical knowledge on TB was highly associated with the long patient delay. Conclusion: Patient delay observed among pastoralist TB patients in SRS is high, exceeding two years in some patients. Lack of access to health care and limited awareness of the disease was the major contributing factors for this delay. This implies the necessity of scaling up Information Education and Communication (IEC) activities to initiate awareness of the disease in pastoralist communities. This compounded with extension of DOTs service to pastoralist dominated areas of the region, may minimise the observed long patient delay.