Background In 2009, China changed its health warnings on cigarette packs from side-only text warnings to two text-only warnings on 30% of the bottom of the front and back of the pack. Also in 2009, Malaysia changed from similar text warnings to pictorial health warnings consistent with Framework Convention on Tobacco Control (FCTC) Article 11 Guidelines.

Objective To measure the impact of the change in health warnings in China and to compare the text-only health warnings to the impact of the pictorial health warnings introduced in Malaysia.

Methods We measured changes in key indicators of warning effectiveness among a longitudinal cohort sample of smokers from Waves 1 to 3 (2006–2009) of the International Tobacco Control (ITC) China Survey and from Waves 3 to 4 (2008–2009) of the ITC Malaysia Survey. Each cohort consisted of representative samples of adult (≥18 years) smokers from six cities in China (n=6575) and from a national sample in Malaysia (n=2883). Generalised Estimating Equations (GEE) were used to examine the impact of the health warnings on subsequent changes in salience of warnings, cognitive and behavioural outcomes.

Findings Compared to Malaysia, the weak text-only warning labels in China led to a significant change in only two of six key indicators of health warning effectiveness: forgoing cigarettes and reading the warning labels. The change to pictorial health warnings in Malaysia led to significant and substantial increases in five of six indicators (noticing, reading, forgoing, avoiding, thinking about quitting).

Conclusions The delay in implementing pictorial health warnings in China constitutes a lost opportunity for increasing knowledge and awareness of the harms of cigarettes, and for motivating smokers to quit.