•MPH is a very effective treatment for ADHD but there are concerns about potential adverse effects of extended treatment on several systems, including growth.•Long term MPH appears to be associated with a statistically significant impact on height and weight in ADHD children and adolescents, but effect sizes are small, with possible minimal clinical effect.•Sensitivity analysis did not reveal a significant effect of dose, age and drug naïvity condition as possible clinical moderators.•Data on effect on pubertal maturation, although limited, seem to favour the exclusion of a possible drug effect on sexual maturation in ADHD subjects.•Current clinical practice guidelines indicate the need of a careful assessment of growth parameters before starting stimulant treatment and the periodic monitoring using standardised growth charts. Particular caution should be taken in pre-school children. Methylphenidate (MPH) is an efficacious treatment for ADHD but concerns have been raised about potential adverse effects of extended treatment on growth. To systematically review the literature, up to December 2018, conducting a meta-analysis of association of long-term (> six months) MPH exposure with height, weight and timing of puberty. Eighteen studies (ADHD n = 4868) were included in the meta-analysis. MPH was associated with consistent statistically significant pre-post difference for both height (SMD = 0.27, 95% CI 0.16-0.38, p < 0.0001) and weight (SMD = 0.33, 95% CI 0.22-0.44, p < 0.0001) Z scores, with prominent impact on weight during the first 12 months and on height within the first 24-30 months. No significant effects of dose, formulation, age and drug-naïve condition as clinical moderators were found. Data on timing of puberty are currently limited. Long-term treatment with MPH can result in reduction in height and weight. However, effect sizes are small with possible minimal clinical impact. Long-term prospective studies may help to clarify the underlying biological drivers and specific mediators and moderators.