Physical inactivity is a global problem which is related to many chronic health disorders. Physical activity scales which allow cross-cultural comparisons have been developed. The goal was to assess the reliability and validity of a Turkish version of the International Physical Activity Questionnaire (IPAQ). 1,097 university students (721 women, 376 men; ages 18-32) volunteered. Short and long forms of the IPAQ gave good agreement and comparable 1-wk. test-retest reliabilities. Caltrac accelerometer data were compared with IPAQ scores in 80 participants with good agreement for short and long forms. Turkish versions of the IPAQ short and long forms are reliable and valid in assessment of physical activity.