Any substance may become a contaminant when occurring at a significantly higher concentration than the natural background level in a particular area or organism. Some contaminants exist naturally in the wild, while others are introduced or released into the environment by human activities. One major concern regarding contaminants is their persistence in the marine environment and subsequent accumulation in seawater, sediments and biota. Due to public health concerns, research on the accumulation of contaminants in marine fish is chiefly conducted on economically important species. Since ocean sunfishes (Molidae) have a low commercial value worldwide, this group has been mostly overlooked. This chapter explores new and previously available data on the presence of three types of contaminants (biotoxins, trace elements and microplastics) in ocean sunfishes, primarily Mola spp., and identifies knowledge gaps. Evidence indicates Mola spp. and Masturus lanceolatus do not have tetrodotoxin. Ocean sunfish exhibit a selection of trace elements that vary with tissue, sex, size, season and location. Species differences in elemental content also exist between Mola spp. and Ma. lanceolatus. Lastly, microplastic contamination has been found in the stomach contents of 79 percent of Mola spp. examined thus far.