Although cycloserine (CS) is recommended by the World Health Organization as a second-line agent for the treatment of multidrug-resistant tuberculosis (MDR-TB), safety concerns have impeded its uptake by several national TB programmes. Terizidone (TRD), a structural analogue of cycloserine, may be better tolerated. To assess the safety of CS and TRD for TB treatment, a systematic review and meta-analysis were conducted. From articles published up to December 2011, 27 studies with 2164 patients were included in our review of CS use. The pooled estimate for the frequencies of any adverse drug reaction (ADR) from CS was 9.1% (95%CI 6.4-11.7); it was 5.7% (95%CI 3.7-7.6) for psychiatric ADRs, and 1.1% (95%CI 0.2-2.1) for central nervous system (CNS) related ADRs. TRD showed no better to moderately better safety than CS in a systematic review of the available literature. The published evidence suggests that CS is associated with a higher frequency of psychiatric and CNS-related ADRs than other second-line drugs. While data were limited, treatment discontinuation rates appeared to be manageable. There were no significant differences in tolerability by region, study period or combination. As countries review and revise their treatment programmes, CS, and potentially TRD, should be included in MDR-TB treatment regimens. Adequate information on possible ADRs should be provided to patients, their families and attending health care workers. Greater attention to MDR-TB patients' mental health and a significant increase in resources devoted to pharmacovigilance and treatment of MDR-TB are essential.