On YouTube antismoking PSAs are widely viewed and uploaded; they also receive extensive commentary by viewers. This study examined whether such evaluative comments with or without uncivil expressions influence evaluations by subsequent viewers. Results showed PSAs with positive (i.e. antismoking) comments were perceived by smokers as more effective than PSAs with negative (prosmoking) comments. Smokers in the no‐comment condition gave the highest perceived effectiveness score to PSAs. Smokers' readiness to quit smoking moderated the effect of comments on PSA evaluation. Smokers reading negative uncivil comments reported more negative attitude toward quitting and a lower level of perceived risk of smoking than those reading negative civil comments but positive civil and positive uncivil comments did not elicit different responses.