Trade in wildlife is increasingly moving online, which creates significant challenges for monitoring. Numerous reports have highlighted the extent of the trade but they rarely present a methodology to facilitate replication or any form of meta-analysis. Here we present a systematic approach to surveying online trade in wildlife that builds on the well-established systematic evidence review approach. We apply this approach to investigate the online trade in saiga antelope Saiga tatarica horns on Russian-language websites. Of the 419 advertisements, the majority (217, 52%) were from Ukraine, followed by Russia (122, 29%), and were largely offers to sell (254, 61%), and represented one-off advertisements. Trade was identified on 89 websites, with the majority being on classified ads websites (68, 76%), auction.violity.com being the most popular site (156, 37%). Prices varied significantly depending on the country and how the horn was being offered (i.e. by weight or length). It is clear that saiga horn is being traded over the internet, with Ukraine and Russia comprising c. 80% of advertisements on Russian-language websites. Individuals with single advertisements dominate, suggesting website fidelity, although website usage is country-specific, potentially reflecting domestic trade. This suggests country-specific interventions could be particularly effective. A systematic approach for investigating online wildlife trade provides a clear and transparent methodology, and, given data collection is resource-intensive, allows studies to be replicated so that trends can be identified. However, this is only possible if published studies report the methodology used.