Acetylation of lysine (KAc) is a ubiquitous post-translational modification, however the extent and functional impact of this modification, as well as specific acetyl-lysine sites, are largely unknown in the parasite Giardia duodenalis. G. duodenalis is responsible for over 200 million cases of diarrhoeal gastroenteritis (giardiasis) annually, and is considered an early-branching eukaryote, possessing basic eukaryotic cellular traits and systems. Here, we report the first analysis of the ‘acetylome’ in this parasite, by comparing acetylation data for the infective trophozoites life-stage during log, stationary and declining phases of axenic culture. Preliminary analyses identified 1747 acetylation sites among 705 unique proteins, including 487, 235 and 153 sites identified uniquely in log, stationary and declining phases, respectively. These data suggest KAc is a widespread modification in G. duodenalis, as acetylated proteins detected thus far constitute 9.47% of non-deprecated gene products in this parasite. Global analysis of sequence motifs indicated enrichment of lysine and neutral amino acids (glycine, leucine and tyrosine) at positions neighbouring KAc. Functional annotation indicated that the majority of the ribosomal machinery is acetylated, as well as the TCP-1 (T-complex protein) chaperone family. A total of 80 acetylated proteins were G. duodenalis kinases, comprising members of Giardia’s reduced core kinome, and the uniquely-expanded Nek kinase family. Many annexin-like proteins from Giardia gene families were also acetylated. These proteins are considered important constituents or accessories of the cytoskeleton, including alpha-giardins, axoneme-associated proteins, NEK kinases and members of the protein 21.1 family. Furthermore, all three peroxidredoxins, and four of five genomically encoded protein disulphide isomerases were acetylated, implicating acetyllysine in the regulation of crucial redox processes in G. duodenalis. This preliminary work will be expanded with additional biological replicates to quantify the reproducibly of identified KAc sites, and complimented with quantitation of the total proteome throughout axenic culture.