The presence of an illicit cigarette trade is used as an argument in Ethiopia to halt pro-health tobacco tax policies. The National Tobacco Enterprise (NTE) recently reported that the illicit cigarette market accounts for over 61% of the total market, and over 90% in the Eastern part of Ethiopia. The aim of the study is to estimate the magnitude of the illicit cigarette trade in Ethiopia. We employed a cross-sectional observational study of empty packs collected in Ethiopia from retailers and from the streets in 10 towns, representing 10 regional states, and two autonomous cities. The majority (80.1%) of the 6438 empty cigarette packs collected (5368 from the streets and 1070 from retailers) belonged to locally produced brands, while the remaining 19.9% were foreign packs, including those allowed to trade in Ethiopia. Overall, 18.9% of the collected empty packs were classified as illicit. However, the share of illicit cigarette packs varied considerably across the country with as many as 97.7% of the packs collected near the Eastern border being illicit. Since the smoking prevalence is significantly higher in that part of Ethiopia, the weighted estimate of illicit cigarette market reached 45.4%. To address this alarming situation, Ethiopia should adopt technologies such as a track and trace system to control its cigarette supply chain, because cigarette packs currently bear no indication that the proper tax was paid. In addition, law enforcement and border security need to be strengthened, especially in the East. This is the first study to estimate the magnitude of the illicit cigarette trade in Ethiopia. It shows that the illicit cigarette trade is low in most parts of the country, but points to some problematic areas near the border with Somalia where illicit cigarette prevalence and overall smoking prevalence are high. We propose a solution to control illicit cigarette trade in Ethiopia that the whole region would benefit from.