Early intervention for autism spectrum disorder (ASD) tends to focus on enhancing social-communication skills. We report the acceptability, feasibility and impact on child functioning of a new 8 weeks parent-group intervention to manage restricted and repetitive behaviours (RRB) in young children with ASD aged 3-7 years. Forty-five families took part in the pilot RCT. A range of primary and secondary outcome measures were collected on four occasions (baseline, 10, 18 and 24 weeks) to capture both independent ratings and parent-reported changes in RRB. This pilot established that parents were willing to be recruited and randomised, and the format and content of the intervention was feasible. Fidelity of delivery was high, and attendance was 90%. A fully powered trial is now planned.