Limited herbicide options are available to adzuki bean growers in southwestern Ontario. Six field trials were conducted in Ontario during 2003 and 2004 to evaluate the tolerance of adzuki bean to dimethenamid (1250 and 2500 g a.i. ha-1), S-metolachlor (1600 and 3200 g a.i. ha-1), clomazone (1000 and 2000 g a.i. ha-1), and imazethapyr (75 and 150 g a.i. ha-1) applied pre-emergence. Dimethenamid caused up to 37% visual injury and reduced plant height, shoot dry weight and yield 27, 59 and 52%, respectively. Seed maturity was also delayed by dimethenamid at 2500 g ha-1. S-metolachlor caused up to 34% visual inj ury and reduced plant height, shoot dry weight and yield 27, 48 and 48%, respectively. Clomazone caused 53% visual injury and reduced plant height, shoot dry weight and yield 47, 84 and 78%, respectively. Imazethapyr caused up to 6% visual injury; however, this injury was transient with no adverse effect on plant height, shoot dry weight, seed moisture content and yield of adzuki bean. Based on these results, dimethenamid, S-metolachlor and clomazone applied pre-emergence (PRE) do not have an adequate margin of crop safety for use in adzuki bean at the doses evaluated. However, imazethapyr applied PRE has an adequate margin of crop safety for weed management in adzuki bean production in Ontario at the doses evaluated. Key words: Clomazone, dimethenamid, imazethapyr, S-metolachlor, tolerance