In a comparative study of Saguinus mystax and Saguinus fuscicollis, we examined the spectrum of plant species whose seeds are dispersed by these two tamarin species. We characterize these plants in terms of life form, fruit colour, pulp consistency and seed dimensions. The tamarins disperse a much broader spectrum of plant species than previously reported (88 of the total of 155 species exploited for fruit). While the distribution over plant life form, fruit colour and pulp consistency is identical between dispersed plant species and the overall spectrum of consumed plant species, clear differences exist in all seed parameters (length, width, height, volume, mass) except specific weight between dispersed and non-dispersed plant species for both tamarin species. Plant and fruit characteristics and seed parameters of dispersed plant species do not differ between S. mystax and S. fuscicollis, suggesting that their ecological and evolutionary interaction with plants is very similar or identical.