The present research investigated how users' risk perceptions are influenced by product warnings that address a variety of hazard features. With respect to the warnings that inform of latent hazards，which are not well known by many users，it seems that users perceive a product to be less hazardous before they read them than after they have read them. Moreover，it is assumed that users will comply with the warnings for latent hazards less often than for patent hazards，because they are less inclined to believe the warnings in the former case. Thus，the obviousness of hazards is one of important variables that predict user safety behavior. The aims of the research were to examine the effects that the obviousness of hazards has on users' ratings for products and warnings，and to determine which variables are predominant in predicting whether users are willing to comply with the warnings. To this end，96 subjects were asked to respond to 9 questions on 12 product usage instructions containing warnings in which the hazard obviousness was manipulated. The results indicate that the hazard obviousness had a great effect on acceptance and belief of the warning，and intention to comply，but that it had no effect on the perceived hazardousness，or ，the perceived severity and likelihood of injury. Acceptance of the warning was found to be the primary predictor of intention to comply，followed by belief of the warning，cost to comply，and the likelihood of injury.