This study presents a thorough examination of the psychometric properties of the Czech version of the Sport Multidimensional Perfectionism Scale-2 in adolescent athletes. Factorial structure, external validity, and internal consistency were evaluated using a cross-sectional design. In addition, three-month temporal stability was also assessed. The cross-sectional study sample consisted of 243 respondents (50.2% females; mean age 16.40 years). Factorial structure of the Sport-MPS-2 was examined using exploratory factor analysis, evidence for external validity was based on bivariate and canonical correlations with Big Five Inventory-2 (short) and Sport Anxiety Scale-2. The longitudinal part of the study was performed on a subsample of 96 participants. Factorial structure in our sample fully corresponded to the structure suggested by the authors of the instrument. Internal consistencies of subscales were satisfactory. Regarding external validity, Doubts about Actions and Concern over Mistakes were positively related to sport anxiety, and positive relationship was found also between Concern over Mistakes and Negative Emotionality. No substantial relationships were found in case of subscales constituting perfectionistic strivings. Temporal stability of Sport-MPS-2 over three months was satisfactory. The Czech version of Sport-MPS-2 can be considered a reliable instrument for assessing perfectionism in sport in the adolescent population.