Fluconazole is a recommended treatment option for the treatment of invasive candidiasis. Fluconazole is active against most pathogenic Candida spp. except C. kruzei and C. glabrata. Fluconazole is orally well absorbed. Its volume of distribution is reported to be 0.7-1.0 L/kg and it is weakly bound to plasma proteins. The majority of fluconazole dose is excreted via the kidneys. Usually, fluconazole pharmacokinetics display moderate inter-individual variability. However, in presence of renal dysfunction or in pediatrics patients, fluconazole pharmacokinetics might be difficult to predict. Concentration-efficacy relationships are demonstrated whereas concentration-toxicity relationships are sparse. As a consequence, therapeutic drug monitoring is not routinely recommended but can be useful in certain situations.