<p>Peatland drying, driven by global warming and human impact alters nitrogen (N) cycling, potentially affecting gaseous and fluvial N fluxes, N stores in peat and in the underlying mineral subsoil, as well as the peat and subsoil N content and stable isotope (¹⁵N/¹⁴N) proportions (δ¹⁵N). Complete peat columns may reveal effects of past climatic periods and drainage for forestry on N stratigraphy within the peat. We measured N concentrations and δ¹⁵N values in peat and subsoil at undrained and drained peatlands in Finland. On three peatlands having paired natural and drained sites, we quantified changes in N, ¹⁵N and ¹⁴N storage, and calculated δ¹⁵N values of the lost or gained N for bog having three synchronous layers on undrained and drained sites. There was preferential downward transfer of ¹⁵N in the uppermost peat of drained bog. Also, the subsoil beneath the drained fen had increased δ¹⁵N values compared to undrained site. δ¹⁵N values were generally below zero, except in one bog and in the subsoil under a fen. In peat layers dating to the Mid-Holocene, high dry bulk density, C%, N%, and humification index, coupled with low C/N ratio, were connected to the highest δ¹⁵N values in profile, similarly to those observed at the surface peat δ¹⁵N maxima. Drainage decreased total N content and transferred N from upper peat layers to deeper strata. In opposite to expectations, on peatlands having parallel undrained and drained sites, δ¹⁵N value increase or decrease was not connected clearly to decreased N mass.</p>