The horn fly, Haematobia irritans irritans (Linnaeus, 1758; Diptera: Muscidae), a hematophagous external parasite of cattle, causes considerable economic losses to the livestock industry worldwide. This pest is mainly controlled with insecticides; however, horn fly populations from several countries have developed resistance to many of the products available for their control. In an attempt to better understand the adult horn fly and the development of resistance in natural populations, we used an Illumina paired-end read HiSeq and GAII approach to determine the transcriptomes of untreated control adult females, untreated control adult males, permethrin-treated surviving adult males and permethrin + piperonyl butoxide-treated killed adult males from a Louisiana population of horn flies with a moderate level of pyrethroid resistance. A total of 128,769,829, 127,276,458, 67,653,920, and 64,270,124 quality-filtered Illumina reads were obtained for untreated control adult females, untreated control adult males, permethrin-treated surviving adult males and permethrin + piperonyl butoxide-treated killed adult males, respectively. The de novo assemblies using CLC Genomics Workbench 8.0.1 yielded 15,699, 11,961, 2672, 7278 contigs (≥ 200 nt) for untreated control adult females, untreated control adult males, permethrin-treated surviving adult males and permethrin + piperonyl butoxide-treated killed adult males, respectively. More than 56% of the assembled contigs of each data set had significant hits in the BlastX (UniProtKB/Swiss-Prot database) (E <0.001). The number of contigs in each data set with InterProScan, GO mapping, Enzyme codes and KEGG pathway annotations were: Untreated Control Adult Females – 10,331, 8770, 2963, 2183; Untreated control adult males – 8392, 7056, 2449, 1765; Permethrin-treated surviving adult males – 1992, 1609, 641, 495; Permethrin + PBO-treated killed adult males – 5561, 4463, 1628, 1211. Data is with this article and also available at the National Center for Biotechnology Information (NCBI) Short Read Archive (SRA) through the direct link https://www.ncbi.nlm.nih.gov/sra/SRP131897 or through SRA accession number SRP131897. The adult horn fly transcriptome Shotgun Assembly project has been deposited at DDBJ/EMBL/GenBank under the accession GGLM00000000. The version described in this paper is the first version, GGLM01000000. The overall BioProject ID is PRJNA429442 and the BioSample accessions are SAMN08355023, SAMN08355024, SAMN08355025, and SAMN08355026. Resources in this dataset:Resource Title: Raw reads. File Name: Web Page, url: https://www.ncbi.nlm.nih.gov/sra/SRP131897 RNA was isolated from unfed, newly emerged adult horn flies, including untreated control adult females, untreated control adult males, permethrin-treated surviving adult males and permethrin + piperonyl butoxide-treated killed adult males. Subsequently, a single lane of 2 × 54 bp paired end RNASeq reads were obtained, de novo assembled and annotated. The raw reads are accessible at NCBI׳s SRA through the direct link https://www.ncbi.nlm.nih.gov/sra/SRP131897 or through SRA accession number SRP131897. The adult horn fly transcriptome Shotgun Assembly project has been deposited at DDBJ/EMBL/GenBank under the accession GGLM00000000. The version described in this paper is the first version, GGLM01000000. The overall BioProject ID is PRJNA429442 and the BioSample accessions are SAMN08355023, SAMN08355024, SAMN08355025, and SAMN08355026.