Organotin compounds (OTs) have been used for approximately 50 years as biocides in antifouling ship paints to prevent the settlement of marine organisms. Although initial evaluations suggested a negligible risk to non-target organisms, over the years the global concern regarding the ecological effects led to a phase out in 2008 on the use of organotins as antifoulants in ship paints. However, given the half-times in anoxic sediments, and the high toxicity to several metazoans, organotins are likely to persist for many years in sites with a high TBT legacy and impact sensitive taxa. Here, we aim at reviewing the biological effects of organotins in marine animals, focusing in particular on environmentally relevant low level effects and the associated molecular and biochemical mechanisms of disruption.