Abstract This study was carried out in 2 chest referral clinics in Lagos, Nigeria, between February 2000 and May 2001 to assess the effects of knowledge, attitude, and practice of 168 newly diagnosed tuberculosis (TB) patients on their care-seeking behaviour. At the onset of symptoms patients sought treatment from one or more of the local private orthodox and traditional health providers, and patent medicine dealers before presenting at a chest clinic. There was a correlation between the level of knowledge and awareness of TB with time of presentation at the chest clinic. Of the 32 patients who presented and were diagnosed at the chest clinics within 4 weeks of onset of symptoms, 50% had knowledge of the aetiological agent of the disease and 60% had some idea of the mode of transmission. Of the 105 patients who presented and were diagnosed 12 weeks after the onset of symptoms, 97% had no knowledge of the aetiological agent and 95% had no idea of the mode of transmission. Overall there was a low level of knowledge and awareness of the disease as well as an apparently high level of improper health care-seeking behaviour amongst the patients studied which probably contributed significantly to the delay in early and accurate diagnosis of most of the cases. These findings indicate an urgent need to educate communities and care providers on the cause and mode of transmission of TB, and the need to attend designated health facilities for early diagnosis and proper treatment.