The 16th Australasian Conference on Information Security and Privacy, ACISP2011 is held in RMIT University, Melbourne, Australia. There were 103 submittions and 24 papers were accepted as full papers and 10 papers were selected as posters (posters are required A1 landscape format, laminated and were affixed to display boards in the same room that the lunch took place). The topics included were symmetric-key cipher, hash functions, PKE, Key Agreement and so on. There were about 8 participants from Japan, and almost all Japanese participants were from industry (Hitachi, NTT, NEC, Sony). The conference orgnized the social dinner in Berth Restaurant, Docklands, Melbourne (with delicious Australasian wine and a course meal). Next ACISP will be held in 2012 at the University of Wollongong, Sydney.