There has been a worldwide increase in multiple drug-resistant tuberculosis (MDR-TB) which has in the past been associated with a poor prognosis. In the U.K., about half of the cases live in the London area and we have set out to obtain further information on their treatment and outcome. We examined the risk factors, drug resistance, drug treatment, sputum conversion, and outcome in patients with MDR-TB at three hospitals in South London and diagnosed during the period June 1995-January 1999. Human Immunodeficiency Virus (HIV)-positive patients were excluded. There were 760 patients resident in Lambeth, Southwark and Lewisham Health Authority (LSLHA) who were notified as tuberculosis (TB) during the time period and who were of negative or unknown HIV status. (The population of LSLHA is approx.750,000.) There was a total of 13 patients with MDR-TB, known or presumed to be HlV negative. Their median age was 28 years (range 15-53); nine (69%) were born outside the U.K. and 11 had pulmonary disease; they had organisms resistant to a median of two first-line drugs (range 2-4) and to a median of four of all drugs tested (range 2-10). They received treatment with a median of six drugs (range 3-9). Eight were followed up for at least 3 years (range 3-6) after the completion of treatment; at their last assessment none had features of active TB and all were sputum negative (smear and culture). Two returned to their countries of origin during treatment; they were sputum negative at that time. Two patients are well and continue on treatment in the U.K. One patient (known HIV negative) died following treatment failure. In conclusion, we obtained disease-free survival in eight cases of MDR-TB, known or presumed to be HIV negative and followed up for 3 years or more. The prognosis for patients treated at specialised centres is good (and better than is generally believed). We describe a new protocol for the detection and management of MDR-TB.