While governmental regulations based on established damage-risk criteria are in place to protect the hearing of people occupationally exposed to toxic levels of noise, guidelines for protection against recreational noise exposure are limited. Previous literature has documented that personal stereo systems (headphones) are capable of delivering potentially toxic levels of sound under certain conditions, but no clinically applicable guidelines are available for the hearing healthcare provider to recommend responsible use. This study sought to measure output levels from a variety of manufacturers of personal stereo systems and several different styles of headphones and calculate the theoretical listening duration and volume control setting that would constitute a hazardous noise dose. Findings indicated variation in output levels among CD player manufacturers and systematic differences in output levels depending on the style of headphone. All CD players studied were capable of delivering sound levels that could result in toxic noise exposure given sufficient listening duration. Guidelines constituting responsible portable CD player use are provided for specific CD players and headphones at various volume control settings.