Because of the possible involvement of bacteria from raw cotton in the causation of byssinosis, we have been investigating the numbers and kinds of bacteria on U.S.-produced raw cotton fiber. Counts for viable bacteria are reported here on commercial raw cotton samples representing fiber grown across the U.S. Cotton Belt in the crop of 1984. The same methods of counting were used as on similar series of samples from the crops of 1980, 1981, and 1982. Many samples with high total bacterial counts were encountered in the 1994-crop series than in any of the three earlier series, also a moderately increased number of samples with high counts for gram negatives. These results appear to be in accord with the fact that open bolls were exposed to an unusually large number of rainy days before harvest in large parts of the Cotton Belt in the fall of 1984. Presumptive coliform is were again detected in most samples of the 1984 crop as a small subgroup of the gram negatives. Counts for samples from the San Joaquin Valley of California were below the Beltwide average, as in previous years. Relations of bacterial counts to weather conditions in the field before harvest are discussed.