Primate seed dispersal in South African forests and its potential benefit to forest plants has not been extensively investigated. South African forests are inhabited by only one exclusively forest-dwelling, large-bodied, diurnal, frugivorous primate, the samango monkey (Cercopithecus mitis). Our study presents first insights into seed dispersal by samango monkeys in an Afromontane forest in their northernmost South African distribution. Through focal animal sampling we found that samango monkeys were predominantly frugivorous (72% of observed feeding time), consuming fruits of 25 plant species and dispersing the seeds of 13 (52%) of them through defecation, carrying in cheek pouches and spitting and dropping. The overall ratio of seed predation was relatively low (16%). Although our study spanned the wet season only, our findings demonstrate that samango monkeys may be potentially important seed dispersers for certain plant species (Ficus spp. and Searsia chirindensis making up 44% of the diet) in this part of their range.