Wellens' syndrome is an electrocardiographic pattern of T-wave changes associated with critical stenosis of the proximal left anterior descending artery, signifying imminent risk of an anterior-wall myocardial infarction. The Wellens' electrocardiographic pattern can also be noted in several cardiac and non-cardiac diseases. We chronicle here a unique case of a patient who presented with atypical left chest pain and dizziness for 6 hours. His pain started after he smoked phencyclidine-laced cannabis. Cardiac panel demonstrated normal troponin T levels. Electrocardiogram showed sinus rhythm with new deep biphasic T-wave inversions in anterolateral leads. Coronary angiography showed no pathological processes. Subsequently, ECG changes resolved coincidentally with the resolution of chest pain. He was eventually diagnosed with pseudo-Wellens' syndrome. This paper illustrates that physicians should be vigilant for Wellens' syndrome mimicked by acute phencyclidine and cannabis intoxication. Additionally, we present a review of various aetiologies of pseudo-Wellens' syndrome, especially in patients with substance abuse.