A model infection with
Candida albicans
was established in mice. The animals were pretreated for 1 week with azathioprine, given dexamethasone, and then infected intravenously with
Candida
. Mortality for the group given
Candida
infection alone was 20%, 38% when azathioprine was added, and 50% when dexamethasone and azathioprine were given with infection. The titers of
Candida
in most mice were 10
6
per gram of kidney. The rest of the mice were killed at 30 days. At this time, 16% had no evidence of
Candida
in the kidneys, but 40% of the mice had titers of 10
6
or more. Mice treated with 5-fluorocytosine had a mortality of less than 4% in 30 days. Five percent of the treated mice killed at 30 days had titers of
Candida
of 10
6
. Therefore, 5-fluorocytosine increases survival in the presence of continued therapy with azathioprine with or without pretreatment with dexamethasone. The survival is associated with decreased titers of
Candida
in the kidneys.