Background:
Illicit trade is one of the main obstacle to tobacco tax and other tobacco control policy reform in Vietnam. The tobacco industry gives different estimates on the size of illicit trade and claims that increasing tax will only drive smokers to illicit products and increase government revenue loss. This study examines the illicit cigarette consumption in Vietnam and its related factors.

Methods:
Data used in this research were from the Global Adult Tobacco Survey conducted in Vietnam in 2015. This is a national representative survey with sample size of nearly 9000 individuals. Descriptive statistics analysis was carried out to estimate the size and examine the patterns of illicit cigarette consumption.

Results:
The estimated market share of illicit cigarettes in Vietnam is 26%. More illicit cigarette consumption was found in urban area and in provinces in the south.
The average price of illicit cigarettes was 50% higher than the average price of legal cigarettes. This suggests that price is not the driving factor in choosing to use illicit cigarettes. This result different from other countries in the region where usually illicit cigarettes are cheaper.
There is no significant difference in age, asset-index quintile between illicit and legal cigarette smokers.
64% of illicit cigarette smokers reported buying from kiosks, 34% reported buying from tea stalls and street vendors. This suggest illicit cigarettes can be accessed rather easily in domestic market.

Conclusions:
As illicit cigarettes are more expansive and price is not the driving factor, tax on cigarettes can be increase higher to reduce total consumption without having too much impact on the illicit trade market.
Smuggling control activities should be reinforced in domestic markets to reduce the easiness of smokers in seeking and buying illicit cigarettes.