The study was undertaken to estimate the marketing costs to ascertain the marketing of onion cultivation in Bellary and Dharwad districts. Multistage sampling technique was adopted and 120 sample farmers were selected randomly comprising 38 small, 38 medium and 44 large farmers. The information on marketing costs included expenses incurred by the sample farmers on various market operations like loading and unloading, transport cost, commission and miscellaneous expenses. The study also included opinions of farmers regarding the problems of marketing of onion.