In continuation of byssinosis-related microbial research, viable counts were made for total bacterial population, gram negatives, and presumptive coliforms on 150 individual samples obtained from the USDA Agricultural Marketing Service to represent the U.S. cotton crop of 1986. As in previous crops, bacterial counts continued to be highly variable within any particular grade at a single location. Data averages, however, showed that the levels for total bacteria and gram negatives were distinctly higher for the 1986 crop than for the crops of 1984 and 1985 and that all three of these crops exhibited higher averages for these bacteria than the crops of 1980, 1981, and 1982. No geographical areas have been observed in which gram negatives regularly constituted an exceptionally high or exceptionally low proportion of the total bacterial population. Presumptive coliforms were observed very generally in the 1986 crop, as in earlier crops, but again only at low or very low levels. The data presented and reviewed suggest that cotton from the U.S. crops of 1984, 1985, and 1986 may have had a higher potential for generating byssinosis in cotton mills than cotton from the crops of 1980, 1981, and 1982.