Purpose: The purpose of this study was to report the opinions and self-reported practices of clinicians, as well as the availability of decision support tools, regarding appropriate thromboprophylaxis for patients with lung cancer to identify variation in practice and/or divergence from evidence-based clinical practice guidelines (CPG). Methods: A computer-generated survey (SurveyMonkey software) was distributed to surgical, radiation and medical oncologists with lung cancer specialisation, via membership of the Australian Lung Cancer Trials Group (ALTG) from May to September 2013. Results: Seventy-two clinicians, from public, private, specialist and general hospitals, completed the survey (46 response rate). Hospital-endorsed CPG were widely available (91 ); however, these routinely lacked robust recommendations for the ambulatory care setting (98 ) and risk stratification tools (65 ). Clinicians consistently identified ambulatory care treatment modalities (chemotherapy, alone or in combination with radiotherapy) as having similar (high) thrombotic risk as surgery. Timing and duration of pharmacological thromboprophylaxis prescribing among surgical oncologists varied and were divergent from guideline recommendations. Fifty-eight percent of surveyed clinicians cited a lack of high-quality data to guide preventative strategies in lung cancer patients. Conclusion: Clinicians consistently identified patients with lung cancer as having a high thromboembolic risk in both ambulatory and surgical settings, but with differences in recommendations and variation in practice. CPG lacked robust recommendations for the ambulatory care setting, the main arena for the multimodality lung cancer treatment paradigm.