Fetal and neonatal inflammation is associated with several morbidities of prematurity. Its relationship to retinopathy of prematurity (ROP) has not been investigated. Our objective was to determine the relationship between cytokine levels and ROP in the first 3 postnatal wks. Data for this study were derived from the NICHD Cytokine Study. Dried blood spots (DBS) were obtained from infants <1000 g on days 0-1, 3 +/- 1, 7 +/- 2, 14 +/- 3, and 21 +/- 3. Infants were classified into three groups-no, mild, and severe ROP. Multiplex Luminex assay was used to quantify 20 cytokines. Temporal profiles of cytokines were evaluated using mixed-effects models after controlling for covariates. Of 1074 infants enrolled, 890 were examined for ROP and 877 included in the analysis. ROP was associated with several clinical characteristics on unadjusted analyses. Eight cytokines remained significantly different across ROP groups in adjusted analyses. IL-6 and IL-17 showed significant effects in early time periods (D0-3); TGF-beta, brain-derived neurotrophic factor (BDNF), and regulated on activation, normal T cell expressed and secreted (RANTES) in later time periods (D7-21) and IL-18, C-reactive protein (CRP), and neurotrophin-4 (NT-4) in both early and later time periods. We conclude that perinatal inflammation may be involved in the pathogenesis of ROP.