Onychomycosis increases the risk of developing secondary bacterial infection and cellulitis if left untreated. The aim of this study was to determine the prevalence of onychomycosis among diabetics and its associated factors. A cross sectional study using universal sampling of all type 1 and 2 diabetic patients attending a primary care facility of the Universiti Kebangsaan Malaysia (UKM) from January to March 2011 was conducted. Samples were taken from clinically abnormal nails and from the first right toenail in the absence of nail abnormalities and cultured for fungal elements. A total of 151 diabetics participated in the study. The mean patient age was 60.7 +/- 9.1 years. A total of 123 nail samples (81.5%) were culture positive for fungal elements. A positive correlation was found between onychomycosis and increasing age (p = 0.011) and clinically abnormal nails (p < 0.05). There were no significant correlations with gender, ethnic group, duration of diabetes, types of diabetes or glycemic control. The prevalence of onychomycosis among diabetics in our study was high.