In this chapter, the novel findings on interrelationship between vitamin D status and two well-known prothrombotic states, antiphospholipid syndrome, particularly its thrombotic phenotype, and metabolic syndrome will be reviewed. We shall present the results obtained from patients included in Serbian National Antiphospholipid Syndrome Registry, 68 patients with primary antiphospholipid syndrome (PAPS) and 69 patients with antiphospholipid syndrome associated with certain autoimmune rheumatic disease (sAPS), as well as 50 patients with pure metabolic syndrome (MetS). These results will be analysed and compared with the novel literature data. Prevalence of MetS in APS is high, with the atherogenic dyslipidaemia as its most prevalent characteristic. Prevalence of thrombotic events was significantly higher in APS patients with coexisting MetS, compared with those without MetS. Among APS patients, prevalence of VitD deficiency was significantly higher than in patients with pure MetS.VitD level was also significantly lower in APS patients with coexisting MetS or previous thrombotic events than in those without them. Elucidating interrelationships between VitD deficiency, MetS and thrombotic events in APS patients open up the possibility of distinguishing those subjects with the particularly high cardiovascular risk and ensuing need for the strict control of modifiable risk factors and VitD supplementation.