A Basidiomycota endomycorrhizal fungus, Piriformospora indica Verma, colonizes and promotes the growth of canola (Brassica napus L.) and other Brassica crops and can reduce diseases of other crops. Clubroot is an important disease of Brassica crops caused by the obligate, soil-borne pathogen Plasmodiophora brassicae Woronin. The effect of P. indica on clubroot severity in canola was assessed in replicated growth room studies. Seed was treated with P. indica using a proprietary process. Microscopic observation confirmed that canola roots grown from treated seed were colonized by P. indica; however, P. indica did not consistently reduce clubroot severity and did not promote the growth of canola.