Since the relation between conscientiousness and dark triad characteristics (Machiavellianism, narcissism, psychopathy) with dimensions of perfectionism has not yet been checked in Croatia, the goal of this research was to examine the differences in conscientiousness and dark triad characteristics between adaptive and maladaptive perfectionists. In addition, the research tries to examine if there is a connection between dimensions of perfectionism with dark triad characteristics and conscientiousness. Adaptive perfectionists set high goals that are achievable and adapted to the context. These individuals are intrinsically motivated and they approach the problem relaxed and with systematical thinking. A successfully completed task gives them a sense of satisfaction and in case of failure, they change their work strategy. Maladaptive perfectionists also set their goals high, but in this case, they are unrealistic and unachievable. They are motivated with fear of failure and focused on avoiding mistakes while working. With failure comes anxiety and the sense of less self-worth. Since dark triad characteristics and maladaptive perfectionism are characterized by common pathological traits, it is assumed that adaptive perfectionists are more conscientious while maladaptive have dark triad characteristics. In addition, it is assumed that adaptive perfectionism will have a positive correlation with conscientiousness and Machiavellianism, while maladaptive will correlate with Machiavellianism and narcissism. It is assumed that psychopathy is not connected with dimensions of perfectionism. The research has been conducted on 246 students from different study groups at the University of Zadar. The following measuring instruments were used: the Short Dark Triad, Positive and Negative Perfectionism Scale (PNPS) and items from the Big Five Inventory (BFI) that concern conscientiousness. Using the T-test it was established that groups of adaptive and maladaptive perfectionists differ significantly, statistically speaking, regarding the expression of narcissism and conscientiousness. Adaptive perfectionists have more conscience and they are also more narcissistic. The results show that there is a significant positive connection between adaptive perfectionism and Machiavellianism, conscientiousness and narcissism. While maladaptive perfectionism is positively connected with Machiavellianism, it is negatively connected with conscientiousness.