Objective. To conduct a literature search for selected biomarkers on preterm delivery and estimate their likelihood ratios (LR). Design. Structured review. Population. Low and high-risk populations and women with symptoms of preterm delivery. Methods. Publications were identified in PubMed. Main outcome measures. LR on selected biomarkers for preterm delivery. Results. In asymptomatic women with low risk of preterm delivery, the following biomarkers gave major shifts in probability (LR above 5): twins (LR+ 10), Ureaplasma urealyticum in amniotic fluid (LR+ of 10), cervical length <25mm (LR+ 6), salival estriol (LR+ 5) and various combined tests. In asymptomatic women with high risk of preterm delivery, short cervical length (LR+ 11, LR– 0.7), high serum tumor necrosis factor-alpha (LR+ 10, LR– 0.6) gave major shifts in probability. In women with symptoms of preterm delivery, major shifts in probability can be obtained from the following amniotic fluid biomarkers: high matrix metalloproteinase-8 (LR+ 23, LR– 0.6), Ureaplasma urealyticum (LR+ 19, LR– 0.8), high interleukin (IL)-6 (LR+ 9, LR– 0.2), IL-8 (LR+10, LR– 0.2) and tumor necrosis factor-alpha (LR+ 8, LR– 0.4). In serum IL-6 (LR+ 12, LR– 0.2), Cluster of Differentiation 163 (LR+9, LR-0.8) and various combined tests. Vaginal fetal fibronectin (LR+ 3 and LR– 0.5) and short cervical length (LR+ 2, LR– 0.3) gave LRs of some importance (LR below 5). Conclusion. Several biomarkers have been identified for assessment of risk of preterm delivery. Their clinical relevance depends on the efficacy of the interventions which can be offered to these patients.