ObjectiveTo assess the incidence of and risk factors for adverse long‐term neurodevelopmental outcome in complicated monochorionic pregnancies treated with selective feticide at our centre between 2000 and 2011.DesignObservational cohort study.SettingNational referral centre for fetal therapy (Leiden University Medical Centre, the Netherlands).PopulationNeurodevelopmental outcome was assessed in 74 long‐term survivors.MethodsChildren, at least 2 years of age, underwent an assessment of neurologic, motor and cognitive development using standardised psychometric tests and the parents completed a behavioural questionnaire.Main outcome measuresA composite outcome termed neurodevelopmental impairment including cerebral palsy (GMFCS II‐V), cognitive and/or motor test score of <70, bilateral blindness or bilateral deafness requiring amplification.ResultsA total of 131 monochorionic pregnancies were treated with selective feticide at the Leiden University Medical Centre. Overall survival rate was 88/131 (67%). Long‐term outcome was assessed in 74/88 (84%). Neurodevelopmental impairment was detected in 5/74 [6.8%, 95% confidence interval (CI), 1.1–12.5] of survivors. Overall adverse outcome, including perinatal mortality or neurodevelopmental impairment was 48/131 (36.6%). In multivariate analysis, parental educational level was associated with cognitive test scores (regression coefficient B 3.9, 95% CI 1.8–6.0). Behavioural problems were reported in 10/69 (14.5%).ConclusionsAdverse long‐term outcome in survivor twins of complicated monochorionic pregnancies treated with selective feticide appears to be more prevalent than in the general population. Cognitive test scores were associated with parental educational level.Tweetable abstractNeurodevelopmental impairment after selective feticide was detected in 5/74 (6.8%, 95% CI 1.1–12.5) of survivors.