New Zealand has one of the highest rates of Crohn’s Disease (CD) in the world, and there is much speculation as to why this might be. A high risk of CD has been associated with deficient or insufficient levels of Vitamin D (Vit D), lifestyle as well as various genetic polymorphisms. In this study we sought to analyse the relevance of serum Vit D levels, lifestyle and genotype to CD status. Serum samples were analysed for 25-OH-Vitamin D levels. DNA was isolated from blood and cheek-swabs, and Sequenom and ImmunoChip techniques were used for genotyping. Serum Vit D levels were significantly lower in CD patients (mean = 49.5 mg/L) than those found in controls (mean = 58.9 mg/L, p = 4.74 × 10−6). A total of seven single nucleotide polymorphisms were examined for effects on serum Vit D levels, with adjustment for confounding variables. Two variants: rs731236[A] (VDR) and rs732594[A] (SCUBE3) showed a significant association with serum Vit D levels in CD patients. Four variants: rs7975232[A] (VDR), rs732594[A] (SCUBE3), and rs2980[T] and rs2981[A] (PHF-11) showed a significant association with serum Vit D levels in the control group. This study demonstrates a significant interaction between Vit D levels and CD susceptibility, as well as a significant association between Vit D levels and genotype.