There is a strong inclination towards using shorter scales for assessment of personality traits. Big Five Inventory scale with 10 items (BFI-10) exhibited good psychometric properties in several countries. The objective of this research was to assess validity and reliability of the BFI-10 questionnaire, translated in Slovenian language. For this purpose, an online survey was conducted among the students and smart phone users. Low correlations between items measuring openness and agreeableness were found and this resulted in low validity and reliability of measuring these two dimensions. Confirmatory factor analysis resulted in severe problems with fitting the model. To overcome these difficulties substitutional items for measuring each personality dimension were introduced and final confirmatory factor analysis model fitted the data well. The modifications of the original scales seem promising for future use.