1. Wildlife-documentary production has expanded over recent decades, while studies report reduced direct contact with nature. The role of documentaries and other electronic content in educating people about biodiversity is therefore likely to be growing increasingly important. This study investigated whether the content of wildlife documentaries is an accurate reflection of the natural world and whether conservation messaging in documentaries has changed over time.2. We sampled an online film database (n = 105) to quantify the representation of taxa and habitats over time, and compared this with actual taxonomic diversity in the natural world. We assessed whether the precision with which an organism could be identified from the way it was mentioned varied between taxa or across time, and whether mentions of conservation and anthropogenic impacts on the natural world changed over time.3. Mentions of organisms (n = 374) were very biased towards vertebrates (81.1% of mentions) relative to invertebrates (17.9% of mentions), despite vertebrates representing only 3.4% of described species, compared to 74.9% for invertebrates.Mentions were highly variable across groups and between time periods, particularly for insects, fish and reptiles. Plants had a consistently low representation across time periods. 4. A range of habitats was represented, the most common being tropical forest and the least common being deep ocean, but there was no change over time.5. Mentions identifiable to species were significantly different between taxa, with 41.8% of mentions of vertebrates identifiable to species compared with just 7.5% of invertebrate mentions and 10% of plant mentions. This did not change over time.6. Conservation was mentioned in 16.2% of documentaries overall, but in almost 50% of documentaries in the current decade. Anthropogenic impacts were mentioned in 22.1% of documentaries and never before the 1970s. 7. Our results show that documentaries provide a diverse picture of nature with an increasing focus on conservation, with likely benefits for public awareness. However, they overrepresent vertebrate species, potentially directing public