To describe the impact of periventricular leukomalacia (PVL) on gross motor function, data on 59 children (37 males, 22 females) with a gestational age (GA) of 34 weeks or less with cerebral palsy (CP) due to PVL grade I (n=20), II (n=13), III (n=25), and IV (n=1) were studied; (mean GA 29 wk 4d [SD 4 wk 6d]; mean birthweight 1318 g [SD 342]). Two independent raters used the Gross Motor Function Classification System (GMFCS) at four time points: T1, mean corrected age (CA) 9 months 15 days (SD 2 mo 6d); T2, mean CA 16 months (SD 1 mo 27 d); T3, mean CA 24 months 27 days (SD 2 mo 3d); and T4, median age 7 years 6 months (range 2 y 2 mo-16 y 8 mo). Interrater reliability and stability across time with respect to the total cohort were kappa>or=0.86 and rho>or=0.74 respectively. The association between PVL and gross motor outcome at T4 was strong (positive and negative predictive values 0.92 and 0.85 respectively). The proportion of children who remained in the same GMFCS level increased from 27% (T1-T4) to 53% (T2-T4) and 72% (T3-T4). PVL grade I to II, as diagnosed in the neonatal period, has a better functional mobility prognosis than PVL grade III-IV. These findings have implications for habilitation counselling and intervention strategies.