Tuberculosis (TB) patients with strains common to other recent cases ('clustering') suggest recent transmission. HIV status and age may affect proportions clustered. We investigated TB clustering by HIV and age in a population-based study in Malawi. Among 746 patients, HIV infection increased the proportion clustered. Sex-period-adjusted odds ratios for the association of HIV and clustering were 1.26 (95% CI 0.4-4.1) for ages 15-25 years, 1.40 (0.9-2.3) for 25-50 years and 10.44 (2.3-47.9) for >50 years and remained stable over two periods examined. These results suggest that HIV increases the proportion of TB due to recent transmission in the elderly.