SETTING: University Teaching Hospital, Lusaka, and Ndola Central Hospital, Ndola, Zambia, which implemented active tracing of multidrug-resistant tuberculosis (MDR-TB) patients reported as lost to follow-up (LTFU). OBJECTIVE: To determine 1) the number of patients treated for MDR-TB between 2011 and 2014; 2) the number, proportion, month when LTFU and characteristics of patients registered as LTFU; and 3) final outcomes observed following active patient tracing. DESIGN: Retrospective cohort study. RESULTS: Of 184 patients treated for confirmed MDR-TB, 76 (41%) were reported as LTFU. From 2011 to 2014, the proportions reported each year as LTFU were respectively 21%, 47%, 51% and 39%. Of patients who were LTFU, 43 (57%) had stopped attending the clinic during the intensive phase. These patients were predominantly male, aged 15-44 years, had pulmonary disease and had failed previous treatment. Of 57 (75%) patients with known human immunodeficiency virus (HIV) status, 42 (74%) were HIV-positive, 57% of whom were on antiretroviral treatment. After active patient tracing, 29 (38%) patients could not be found and the observed outcome remained LTFU. Of the remaining 47 patients, 29 (62%) were alive and had completed or were still on treatment, 14 (30%) were alive but had stopped treatment and 4 (8%) had died. CONCLUSION: Zambia has been underreporting its favourable outcomes for MDR-TB treatment and should continue with active tracing of LTFU patients.