We examined the association of the termination of a successful youth-targeted antitobacco media campaign ("truth") and changes in smoking rates among youths aged 12-17 years in Florida. Six telephone-based surveys were completed during the active media campaign (1998-2001), and 2 postcampaign surveys were completed in 2004 and 2006 (each n approximately 1,800). Prevalence of current smoking among youth observed during the campaign continued to decrease in the first postcampaign survey; however, by the second follow-up survey, youth smoking rates had increased significantly for youth aged 16 years or older. Our findings support the need for consistent antitobacco messaging to reduce the prevalence of youth smoking.