Aim: The objective of the present study was to analyze by means of radial arm maze (RAM), a large-scale behavioral and ecological task, the spatial abilities in individuals with Down syndrome (DS) and Williams syndrome (WS). Method: We examined the performances in RAM task of 12 individuals with DS with chronological age (CA) of 17.04 years and mental age (MA) of 6.06 years, and 12 individuals with WS (CA: 16.02 years MA: 6.06 years). Fifteen right-handed typically developing (TD) children, MA matched with DS and WS groups (CA: 6.06 years, MA: 6.05 years), formed the control group. All participants were trained in the free-choice version and in the forced-choice version of the RAM. Results: In the free-choice paradigm, the DS and WS individuals took about 60s more than TD subjects to explore the maze. In spatial span (the longest sequence of correctly visited arms), the syndromic groups obtained lower values than TD children, while only WS individuals made more errors than the other groups. In the forced-choice paradigm, DS and WS groups made more errors than TD children and continued to put into action mainly an algorithmic strategy (enter adjacent arms) even to perform wrong visits suggesting thus an impairment in procedural components. Conclusion: The findings evidenced the impairment of DS and WS individuals in solving the RAM task with variable severity depending on the paradigm requests. Since the RAM is a task that allows the acquisition of spatial competences through the walking, we advance that the spatial deficits observed in these genetic syndromes may be related to the malfunctioning of spatial and motor integrative processing.