This work sought to determine the factors associated to uncertainty in parents of preterm newborns hospitalized in neonatal intensive care units (NICU).This was a cross-sectional analytic study with 117 parents (79 mothers and 38 fathers) of preterm newborns hospitalized in three NICUs of Cartagena (Colombia). Sociodemographic information was included; the biophysical profile of the preterm infant (PTI) and the results from the Mishel Uncertainty in Illness Scale.A high level of uncertainty was found in 49.3% of the mothers and 52.6% of the fathers. The OR lower limits the variables of the parents that were associated to uncertainty were: OR = 2.5 not having a partner and OR = 2.3 having secondary education, plan OR = 2.8 belonging to socioeconomic levels 1 and 2. In the PTI variables, the following were related to uncertainty: weight <1500 gr and mechanical ventilation care, with lower limits of the OR of 1.9 and 1.3, respectively.Nurses must incorporate in the care plan the evaluation and intervention of uncertainty in fathers and mothers of PTIs hospitalized in NICU.