14 April – A massive hailstorm hits Sydney, with most of the damage being centred on the Eastern Suburbs. It is the second most costliest natural disaster in Australian history, causing $1.7 billion in insured damages.
11 May – The biotechnology industry receives a record $800 million in the federal budget.
21 May – Eight decaying bodies are found in barrels in a disused bank vault north of Adelaide, marking the beginning of the Snowtown murders case, which were Australia's worst ever serial killings. More bodies were found underneath a house in Adelaide on 26 May.
28 June – The GST bill is passed through the Senate, with the help of most of the Australian Democrats, in exchange for exemptions on fresh food.
26 August – The Prime Minister creates a controversy when he avoids the use of the word 'sorry' when a motion was tabled in Parliament expressing 'deep & sincere regret that indigenous Australians suffered injustices under the practises of past generations'.
14 November – In response to the growing number of illegal immigrants, most of whom arrived by boat, the government allows police to board vessels in international waters. On 23 November, refugees were barred from seeking asylum in they had lived somewhere else for more than seven days or had the right to live somewhere else.
The Seven Network becomes the first Australian television network to introduce a watermark on its programs, although the watermark is not allowed to be broadcast on news or current affairs programs or Deal Or No Deal from 2004 onwards.
18 March – First day of the Australian Track & Field Championships for the 1998–1999 season, which are held at the Olympic Park in Melbourne, Victoria. The 10,000 metres was conducted at the Zatopek Classic, Melbourne on 5 December 1998. The men's decathlon event was staged at the Hobart Grand Prix on 25–27 February.
25 September – The Kangaroos (19.10.124) defeat the Carlton Blues (12.17.89) to win the 103rd VFL/AFL premiership. It is the first all-Victorian grand final since 1995 & the first time the cup has not been won by the Adelaide Crows since 1996.
26 September – A new world record crown for rugby league is set when 107,961 people attend the first National Rugby League grand final held at Stadium Australia. In one of the most memorable & controversial grand finals in history, the Melbourne Storm, in just their second season of existence, defeat the St George Illawarra Dragons 20–18. The final outcome is determined when a penalty try is given to Melbourne's Craig Smith. Melbourne's win means that both the AFL trophy & NRL trophy have been won by teams from the same city for the first time.
3 October – In the third year of the split in the organisation of the Bathurst 1000 the traditional race was held for the last time and won by Paul Morris as the Bathurst 500 was declared after just 310 of the scheduled 500 kilometres due to unrelenting rain. It was a justification for Morris and the BMW team after being disqualified from victory two years ago.
10 October – South Sydney supporters rally through the streets of Sydney to protest against the rationalisation of the NRL to 14 teams for 2000.