It is estimated that almost 4% of all neonatal intensive care unit admissions are attributed to Candida spp. infections. Clinical diagnosis of invasive fungal infection (IFI) is not easy as signs and symptoms are commonly vague. Mannan antigen (MA) in neonates is not well studied and the aim of this study was to evaluate the use of MA (Platelia™ Candida Ag Plus kit, Bio-Rad) in a neonatal unit. This is a prospective case-control study, which compared the performance of MA between neonates who had rectal Candida colonization with non-colonized controls. We cultured 340 rectal swabs of neonates and 39 of them were positive for Candida albicans colonization. MA was checked in 25 C. albicans colonized and in 30 non-colonized neonates with similar postnatal age and gender distribution. During the hospitalization period there was not any IFI in the neonatal population. MA was negative in all non-colonized neonates (30/30, 100% specificity) and in 24 out of 25 colonized neonates (96% specificity). However, the one infant with positive rectal colonization and MA had recent Candida mucositis. The results indicate a high specificity of the assay even in neonates colonized with Candida. Further investigation in neonates with IFI is required in order to determine the sensitivity of the method.