They qualified for the East Asian Cup and beat South Korea in a friendly, but the Socceroos have slid to 36th in the rankings. Spain, meanwhile, hold on to top spot
Australia have fallen three places in the Fifa world rankings to 36th, while Spain finished on top for the fifth consecutive year.
Despite winning all but one of their East Asian Cup qualifiers and beating South Korea in a friendly, Australia, who started the year in 23rd, dropped to their lowest ranking since November 2008.
The Socceroos climbed as high as 20th in March but have since slipped behind the likes of Zambia, who jumped five places to 34th.
Japan, who claimed a valuable 2014 World Cup qualifying win over Oman, are Asia's highest-placed team in 22nd.
Reigning European and world champions Spain stayed at the summit of the rankings, while Joachim Low's Germany remain in second place.
South American giants Argentina completed the podium.
Euro 2012 finalists Italy have climbed one place and now sit fourth, ahead of Colombia, who were named 'Mover of the Year' after reaching fifth position from 36th at the start of the year.
England are sixth, while Portugal [seventh, three down], Netherlands [eighth, one down], Russia [ninth] and Croatia [10th] complete the rest of the top 10.
Copa America holders Uruguay have to settle for 16th place after dropping five places, while World Cup hosts Brazil are only 18th.
Cote d'Ivoire stay as Africa's highest-placed team at number 14, while Japan are the pride of Asia in 22nd position.
Cuba are this month's biggest climbers as they went 41 places up to make it to 100th spot, while Belize [down 23] dropped the most positions compared to last month's FIFA rankings.