OBJECTIVE: In Singapore, the use of traditional Chinese medicine (TCM) alongside Western medicine (WM) is common. There are risks of adverse herb-drug interactions when taken concurrently. Current literature suggests that TCM use is not regularly reported to WM doctors in Singapore, but the underlying reasons are not understood. METHODS: A cross-sectional study was conducted across Singapore by administering questionnaires to TCM-using patients and WM-practising general practitioners (GPs). The questionnaire examined the following themes: (1) demographics and TCM use pattern; (2) respondents' (patients and GPs) knowledge and beliefs about TCM and the factors influencing the discussion of TCM during the WM consultation; and (3) respondents' qualitative suggestions to increase disclosure rate. RESULTS: A total of 484 patients and 334 GPs were surveyed. Factors associated with patients' initiation of TCM discussion include length of consultation (odds ratio [OR]: 2.1; P < 0.001), comfort level in discussing TCM (OR: 1.6; P < 0.001) and belief in importance of discussion (OR: 1.4; P = 0.017). Doctor's initiation of discussion (74%) was the top patient-ranked factor influencing their discussion of TCM. For doctors, knowledge of TCM indications (OR: 2.2; P < 0.001), belief in importance of discussion (OR: 2.1; P < 0.001) and comfort level in discussing TCM (OR: 1.9; P = 0.001) were associated with their initiation of TCM use discussion. Possible WM-TCM interactions (58%) was the top doctor-ranked factor influencing their discussion of TCM. CONCLUSION The discussion of TCM in a WM setting is multifactorial. Interventions include doctors' active screening for TCM use in patients and equipping doctors with TCM knowledge. Improving communication between patients and doctors is key to avoiding harmful herb-drug interactions.