Background: Respiratory medicine (RM) and palliative care (PC) physicians��� management of chronic breathlessness in advanced chronic obstructive pulmonary disease (COPD), fibrotic interstitial lung disease (fILD) and lung cancer (LC), and the influence of practice guidelines was explored via an online survey. Methods: A voluntary, online survey was distributed to RM and PC physicians via society newsletter mailing lists. Results: 450 evaluable questionnaires (348 (77%) RM and 102 (23%) PC) were analysed. Significantly more PC physicians indicated routine use (often/always) of opioids across conditions (COPD: 92% vs. 39%, fILD: 83% vs. 36%, LC: 95% vs. 76%; all p < 0.001) and significantly more PC physicians indicated routine use of benzodiazepines for COPD (33% vs. 10%) and fILD (25% vs. 12%) (both p < 0.001). Significantly more RM physicians reported routine use of a breathlessness score (62% vs. 13%, p < 0.001) and prioritised exercise training/rehabilitation for COPD (49% vs. 7%) and fILD (30% vs. 18%) (both p < 0.001). Overall, 40% of all respondents reported reading non-cancer palliative care guidelines (either carefully or looked at them briefly). Respondents who reported reading these guidelines were more likely to: routinely use a breathlessness score (��2 = 13.8; p < 0.001), use opioids (��2 = 12.58, p < 0.001) and refer to pulmonary rehabilitation (��2 = 6.41, p = 0.011) in COPD; use antidepressants (��2 = 6.25; p = 0.044) and refer to PC (��2 = 5.83; p = 0.016) in fILD; and use a handheld fan in COPD (��2 = 8.75, p = 0.003), fILD (��2 = 4.85, p = 0.028) and LC (��2 = 5.63; p = 0.018). Conclusions: These findings suggest a need for improved dissemination and uptake of jointly developed breathlessness management guidelines in order to encourage appropriate use of existing, evidence-based therapies. The lack of opioid use by RM, and continued benzodiazepine use in PC, suggest that a wider range of acceptable therapies need to be developed and trialled.