AIM To compare the axial eye length growth of the two fellow eyes within one patient after unilateral paediatric cataract surgery and to assess changes in refraction and keratometry. PATIENTS/METHODS A retrospective study in 90 eyes of 45 patients was performed. The 45 patients were divided into group 1 (patients younger than 18 months at the time of surgery, n=25) and group 2 (patients 18 months or older at the time of surgery, n=20). The axial eye length, spherical equivalent refraction and keratometry were measured during surgery and at follow-up. All outcome data in the operated eyes were compared with the outcome data of the fellow non-operated eyes. The Student t test was used for statistical analysis. Values of p<0.05 were considered statistically significant. RESULTS In group 1 the absolute growth (mm) of the operated eyes was borderline statistically significantly less than in the fellow non-operated eyes (p=0.049). No statistically significant difference in the rate of axial growth between the two eyes was found (p=0.25). A larger myopic shift (p=3.85x10(-5)) and a larger change in keratometry (p=0.02) were found in the operated eyes. In group 2 no statistically significant differences were found between the two eyes. CONCLUSION We did not find a statistically significant difference in axial length growth between the operated eyes and fellow non-operated eyes in our unilateral paediatric cataract patients.