The main aim of the study is a comprehensive assessment of psychometric properties of the Polish version of Perception of Success Questionnaire (POSQ) in sport. Apart from standard psychometric evaluation, the paper presents an analysis of item reliability through the use of Item Response Theory, as well as the analysis of relationships between sport type, level of participation, gender and goal orientation level. The study covered 412 people aged M = 23.46 (SD = 5.40). The Perception of Success Questionnaire (POSQ), the Task and Ego Orientation in Sport Questionnaire (TEOSQ) and the Sport Motivation Scale (SMS-28) were used. High reliability of POSQ ego subscale (α = 0.89, ω = 0.89) and POSQ task subscale (α = 0.90, ω = 0.91) were noted. The test-retest correlations at the two-week interval were ICC = 0.91 for ego subscale, and ICC = 0.71 for task subscale, respectively. Confirmatory factor analysis showed a relatively good fit of the two-factor model to the data (CFI = 0.94). Relationships between the goal orientation measured by the POSQ questionnaire and motivational traits measured by TEOSQ and SMS-28 were obtained. It was also shown that high-performance athletes had higher scores on the ego factor than recreational athletes. Moreover, men had higher scores on the ego factor than women. The Perception of Success Questionnaire (Polish version) is characterized by satisfactory psychometric properties and can be used for scientific research and diagnosis.