A study in 11 primary health care facilities in and around Cape Town determined the proportion of bacteriologically confirmed tuberculosis (TB) cases who did not start treatment (initial default) and identified reasons for it. Databases from centralised laboratories were compared with electronic TB treatment registers. Fourteen per cent (373/2758) of TB suspects were TB cases. Of the 58 (16%) initial defaulters, 14 (24%) died, while 26 (45%) could not be interviewed for address-related reasons. The 18 subjects who were interviewed indicated reasons for initial default that were (56%) or were not (44%) directly linked to services. High initial default rates require improvement in the quality of health services.