Purposes: To identify and synthesize RCTs on the isolated effect of dosage parameters of upper limb Intensive Motor Rehabilitation Treatments (IMRT) of children with Unilateral Spastic Cerebral Palsy (USCP); to identify the most frequent methodological weaknesses. Methods: Searches were conducted until September 2018 in gray and published literature databases and supplemented by exploring the identified studies' references. Inclusion criteria applied: RCT; children aged 1.5 to 19 years with USCP; upper limb IMRT differing only from ≥1/4 dosage parameters between groups. Literature analyses conducted: qualitative and descriptive. Results: We identified 461 studies. Seventeen were included: three presented a rehabilitation dosage distinction between groups in Frequency-Time, four in Intensity-Progressivity, three in Intensity-Restraint, two in Intensity-Environment and five presented ≥3 distinctions above. Conclusions: Inconsistencies were noted between USCP lifelong issues, and the short follow-ups and lack of participation assessments. Confounding factors and misstatements in Intent To Treat (ITT) analyses were identified. A meta-analysis was considered irrelevant.