Persuasive role in Recommendation Systems operates like motivators influencing users to buy the recommended items. In this study, we rely upon the well established explanations of six Cialdini's Principles to enrich recommendation system with explanations and examine their effect on the persuasive power of recommendation item. The results of the experiment revealed that all six Cialdini's Principles positively affect user's influnce about the recommended book while reciprocity and authority seem to be the more effective ones. These indicate that a user's intention to purchase a recommended item is increased if the item is accompanied with a persuasive explanation.