1. Nutrient supplies to plants from ants are well known from specialised myrmecophytic symbioses and from plants growing in soil close to ant nests. However, above ground nutrient pathways may play a hitherto largely unrecognised role also in less specialised ant-plant interactions – the numerous facultative relationships, where ants forage on plants. 2. In a laboratory setupexperiment, weaver ants (Oecophylla smaragdina) were confined to the canopies of coffee (Coffea arabica) seedlings, excluding any ant-to-plant transfer of nutrients via the soil strata. When ants were fed 15N-labelled glycine and subsequently deposited fecal droplets on the seedlings, coffee leaves showed increased levels of 15N and total N compared to control plants without ants. This was evident for both exposed leaves and leaves covered in plastic bags (i.e. not directly exposed to ants). Thus, N from ant excretions was absorbed through the coffee leaves and, subsequently, translocated within the plants and possibly leading to the observed higher shoot/root (wet weight) ratios observed on ant plants compared to controls. 3. Synthesis: These results reveal an hitherto undescribed foliar uptake of ant provided nutrients. If this is a general mechanism, a vast amount of ant plant interactions involves fertilization. This may change our understanding of ant-plant co-evolution. Foliar fertilization by ants may be an important steady benefit to plants, which has driven the evolution of ant-plant mutualisms in parallel with the well-recognised but probably more fluctuating benefit from herbivore protection. Given the worldwide abundance of plant canopies foraged by ants, this nutrient pathway may be of high ecological significance.