Deep vein thrombosis (DVT) is a preventable complication of critical illness, and this guideline aims to convey a pragmatic approach to the problem. Guidelines have multiplied over the last decade, and their utility has become increasingly conflicted as the reader interprets all suggestions or recommendations as something that must be followed. The nuances of grade of recommendation vs level of evidence are often ignored, and the difference between a “we suggest” vs a “we recommend” is overlooked. There is a general unease among clinicians that failure to follow the guidelines translates to poor medical practice and legal culpability. We attempt to overcome these limitations by highlighting ambiguity when it occurs and refraining from dogmatic recommendations in the absence of robust evidence. Readers and practitioners may find the lack of specific recommendations unsatisfactory, but we believe that true ambiguity is better than inaccurate certainty. We have attempted to comply with the guidelines on how to create guidelines.¹ And to overcome the poor compliance with these guidelines.² Some observers have expressed concern that DVT prophylaxis guidelines may cause more harm than good.³ We have placed greater emphasis on large randomized controlled trials (RCTs) with clinical end point and de-emphasized RCTs with surrogate end points and also de-emphasized hypothesis generating studies (observational studies, small RCTs, and meta-analysis of these studies). We have de-emphasized RCTs in non-intensive care unit populations like postoperative patients or those with cancer and stroke. We have also considered resource limitation settings and have avoided recommending costly and poorly proven therapeutic options.