The outcome of successful marketing is an increase in sales and revenue, but the impact of marketing can also be utilized to contribute to positive changes. Example of such a change is encouraging omnivores to eat a plant­based diet. However, most people have a negative attitude towards veganism and remain resistant to change. For more effective marketing campaigns, it is crucial to know the attitudes of the target population, as well as the impact of marketing decisions on the perception of the advertised product. Therefore, the aim of this study was to examine participants ’attitudes about the vegan diet and to determine the impact of marketing on omnivores’ perception of a vegan food product (a cookie) using an experimental design. 1166 participants answered an online survey with different measures of product acceptability and a scale of attitudes towards the vegan diet. The results on indicate that omnivores have a negative general attitude towards the vegan diet, while vegetarians and vegans have a more positive attitude and don’t differ from each other. The same pattern of results holds true on the subscales of the attitudes questionnaire, Benefits and Satisfaction. On the Practicality subscale, all dietary groups differ significantly, with omnivores giving the lowest and vegans the highest estimates. The experimental part of the research found a negative impact of vegan marketing, where omnivores gave significantly lower estimates of buying likelihood if the cookie was presented as vegan. Compared to the control, participants indicate higher expected retail price for the vegan cookie, as well as willingness to pay. Different advertised motivations for producing a vegan cookie didn’t influence any of the estimates. Overall, results indicate that it may not be advisable to emphasize that a product is vegan if the goal is to market the product towards the general population.