The painting of today's thermoplastic olefins (TPO) presents a series of new challenges to paint and part suppliers alike. TPO has shown a dramatic increase as an engineering plastic for exterior automotive parts because of its low density, wide range of moduli, excellent appearance when painted, low cost and recyclability. However, in terms of paintability TPO suffers from a number of disadvantages. The issues of adhesion, mar resistance, contamination, pigmentation and air pollution need to be addressed for painters to keep pace with the rapid growth of TPO as a major substrate for automotive parts. This paper will deal with problems encountered in the day to day painting of TPO, how to analyze them, and some suggestions as to corrective action.