Former All Whites captain Ryan Nelsen is one of a number of footballers named by hackers Fancy Bears as players permitted to use otherwise-banned medicines during the 2010 World Cup.
The ex Blackburn, QPR and Tottenham defender declared the use of prednisone, a corticosteroid.
Prednisone treats many different conditions such as allergic disorders, skin conditions, ulcerative colitis, arthritis, lupus, psoriasis, or breathing disorders, according to drugs.com.
Others named include former Argentine stars Carlos Tevez and Juan Veron and former Dutch striker Dirk Kuyt.
There is no suggestion any of these footballers have done anything wrong.
Fifa said it condemned "in the strongest terms" the release of material it said was obtained illegally, the BBC reports.
"The release of such information constitutes a clear violation of the athletes' privacy and puts at risk the ongoing fight against doping," a statement said.