This study titled, Influence of Sales Promotional Activities on Consumer Behaviour: A Comparative Study of Friesland and Promasidor Companies’ Promotional Activities, set out to measure how sales promotion influences consumer behaviour and to empirically test this on peak and cowbell milk which are products of the two companies under investigation. To achieve this, the survey method was utilized, while questionnaire was used to elicit information from residents of Makurdi metropolis. The study established that the two companies actually embark on sales promotional activities; and majority of the respondents were influenced by the promotional activities on peak and cowbell milk, while a few others were swayed by factors such as income, habits and the quality of the products. More findings showed that most consumers patronize peak milk more than cowbell milk because the decrease in price due to sales promotional activities does not affect its quality. Further findings showed that increase in sales is the most reason why peak and cowbell milk embark on promotions; and the fact that majority of consumers become brand loyalists even after the promotion. The study therefore concludes that promotional activities and sales promotion specifically is a stronghold for the two companies studied especially Friesland. Also, the media to an extent have been very instrumental in promoting peak and cowbell milk. The study therefore recommends that Friesland and Promasidor Companies, the producers of peak milk and cowbell milk should make extensive use of sales promotion as a marketing strategy especially Promasidor hence findings showed that its promotional activities are low compared to Friesland. This is in order to make huge sales and profits among other recommendations.