The high volume instrument (HVITM) instrumental leaf grade index has been accepted in both domestic and international cotton fiber trading. There is interest in how trash content in cotton samples impact the HVI measurements. In this investigation, HVI micronaire attribute was measured on commercial cotton bales representing instrumental leaf grade categories one to six, pre- and post- Shirley Analyzer (SA) cleaning process. The SA system was used since it is a traditional gravimetric cotton trash reference method, and also plays a role as a small-scale cotton trash cleaner. This study first examined the variations of five repeated HVI micronaire measurements within one pre-SA or post-SA cleaned cotton, and it revealed an insignificant effect of trash presence in high instrumental leaf grade cottons on HVI micronaire measurement repeatability. A comparison of HVI micronaire between pre-SA and post-SA cleaned cottons indicated a good agreement, suggesting minimal effect of cotton trash presence in commercial cottons on their HVI micronaire determination. Meanwhile, higher instrumental leaf grade cottons were observed to show lower micronaire values.