The prevalence of Candida infections in paediatric intensive care units (PICUs) has dramatically increased as a result of resistance to conventional anti-fungal treatments. Because vitamin D has been shown to exhibit fungicidal activity against Candida infection in an invitro antimicrobial screening, we aimed to investigate the effect of vitamin D on Candida infections in the PICU. Four hundred sixteen eligible children aged between 12months to 5years old admitted to the PICU, who were on broad-spectrum antibiotic therapy, participated in the study. Patients were randomly assigned to two study groups, receiving a plain yogurt drink (placebo group) or supplemented with 300IUday-1 vitamin D (VD group). Primary outcome was defined as the incidences of Candida colonisation (Candida isolated from rectal swab) 14days after enrollment. Secondary outcome measures were Candida growth in blood (candidaemia) and urine (candiduria). The prevalence of candiduria as well as candidaemia was significantly lower in the VD-treated group (26 cases) than in the placebo group (62 cases). The mean (SD) length of PICU stay was obviously lowered in the VD group [11.8(1.2)days] compared to the placebo group [15.2(2.3days)], whereas cases of patient death were similar between the two groups. Supplementation of vitamin D effectively reduces infections of Candida in children who were critically ill and on broad-spectrum antibiotic treatment.