BACKGROUND: Multiple sclerosis (MS) involves impaired trunk control, leading to impaired upper-limb functionality, dexterity, and independence. Deciding early on a comprehensive approach pointing of functional disturbances and personal needs is essential for a multimodal, individualized, goal-oriented assessment and treatment program, recognizing the broad range of symptoms and disabilities associated with MS. In clinical practice, postural control of the trunk is purported to be an important contributor to voluntary upper-limb function, including motor control and dexterity. The objective of this study was to point out the impairments of and relationship between trunk control and comprehensive upper-limb functions in individuals with MS. METHODS: Tasks that were sought are optimal screening for deterioration in trunk control (Trunk Control Test [TCT] and Trunk Impairment Scale [TIS]) and upper-limb functionality by comparing them with the Expanded Disability Status Scale (EDSS), Nine Hole Peg Test (NHPT), Duruoz's Hand Index (DHI), and Functional Independence Measurement (FIM) results of 49 well-defined relapsing-remitting MS (RRMS) participants with those of 49 age-gender matched healthy subjects. RESULTS: Significant differences between the groups were evident across all tasks of the clinical tests studied (p < 0.05), except the TCT-balance in sitting position subscore. EDSS, NHPT, DHI, and FIM scores were highly correlated with the TCT subscores (rolling to weak side, sitting up from lying down) and TCT-total score, as well as TIS subscores (dynamic and coordination) and TIS total score (p ≤ 0.005). While TIS subscores were highly correlated with almost all parameters, just TIS-static subscore did not correlate with the DHI and FIM-cognitive scores. Also, DHI-hygiene subscore correlated poorly just with the TIS-coordination and TCT-coming to sitting position (p < 0.05). CONCLUSION: We found that patients with MS would present impaired upper-limb movement and decreased trunk control with high correlation between them, even in RRMS and in the very mild form of the disease. Identifying trunk control deficits provides better insight into dexterous difficulties of patients with MS and allows a more targeted neurorehabilitation focusing on upper limbs. In future studies, it would be of interest to examine the prognostic value of trunk control and upper-limb functionality in patients with MS using a longitudinal approach.