1) 148 Dutch mints were assembled, partly from botanical gardens and partly from 12 sources throughout the country, and were cytologically investigated. 2) New chromosome numbers were found for M. arvensis (2n=24) and for M.x dumetorum (2n=72), and fourteen counts were in agreement with the literature. 3) Brief notes on the assembled species and hybrids are given. The distinction of pure and hybrid cytotypes in M. spicata, its variety crispata, and M. rotundifolia seems noteworthy. 4) One form seems to be a new Mentha hybrid, presumably M. rotundifolia x crispata. 5) Some relationships between cytological and morphological aspects are discussed, especially in M. rotundifolia and M.x dumetorum.