This paper reports results of experimental investigations of contamination build-up on slider surfaces and its effects on the performance of tri-pad slider-based near-contact recording systems. Results indicate that the head-disk clearance changes, caused by contamination build-up, can be comparable to the designed head-disk clearance. As a result, the drive's performance and reliability can be strongly affected. Results obtained show that the amount of increase in the value of transition region length parameter is greater than the corresponding increase in head-disk clearance. Consequently, the writing performance suffers more severe degradation than the read performance. This is shown by error rate measurements at the drive level as well as PW50 and NLTS measurements at the component level.