Bull fertility impacts herd fertility, but accurately predicting male fertility from sperm characteristics is difficult once extremes are removed. The objectives of this study are identification, relative quantification, and comparison of sperm head plasma membrane (HPM) proteomics in bulls of differing bull fertility index (BFI). HPM from one fresh ejaculate from 16 Holstein bulls (8 each high and low fertility; HF, LF) was extracted and its proteins were assessed by tandem mass spectrometry. Mass spectra were aligned to UniProtKB mammal database and proteins were identified and characterized by SpectrumMill. Of 22,117 total proteins identified (unique plus homologous; 1% false discovery rate), Mass Profiler Professional statistical analysis identified 67 differentially abundant proteins (DAPs) in the HPM of 3 bulls each with highest and lowest BFI (105.66±0.54, 91.33±1.44, respectively; p<0.01]. DAPs differed in intensity by at least 2-fold (48 up-regulated, 19 down-regulated, HF vs LF) and meta-analysis confirmed their association to BFI. Gene ontology assigned up-regulated proteins to sperm fertilization mechanisms, and down-regulated proteins to catalytic and transporter activity. Linear regression positively correlated BFI of the 6 HF and LF bulls to all up-regulated DAPs (r2=0.65 to 0.97, p≤0.05), and negatively correlated BFI to all down-regulated DAPs (r2=0.76 to 0.96, p<0.05). In the 16-bull population, linear regression positively correlated BFI to 38 of the up-regulated DAPs (r2=0.29 to 0.66; p≤0.05), and negatively correlated 6 of the down-regulated DAPs (r2=0.26 to 0.44; p≤0.05). In summary, this study revealed proteins in HPM, highlighting their significant role in sperm fertilization and correlation with bull fertility.