Medical marijuana has come to Pennsylvania and by extension to the common-wealth's injured workers. What image comes to mind? Do you see an injured construction worker, home-bound due to multiple failed back surgeries, breaking free of opioids and performing daily activities that have eluded him for years? Or do you see a stoner employee blissfully smoking the best pot of his life at his desk, on your dime, because a doctor "recommended" it for minor low-back strain? These scenarios capture the promise and the fear of the introduction of medical marijuana into Pennsylvania's workers' compensation system. By the end of this article, I hope to clear the haze and provide guidance on two burning questions: How will it be determined if the use of medical cannabis is reasonable for an injured worker? And, will workers' compensation carriers be required to pay for or reimburse workers for medical marijuana?