In vitro coffee seedlings were exposed to an electromagnetic field (EMF) of 2 mT during 3 minutes in establishment, multiplication, and acclimazation phases. Shoot and root lengths and leaf pair numbers of treated groups increased when compared to control; in addition to SOD, CAT, and APX activities of in vitro-treated groups showed a decrease in levels. Four months after the magnetic treatment was applied, the same parameters were evaluated. Shoot lengths, root lengths, the pair of leaves numbers, and CAT activity increased in treated plants. APX activity decreased in treatment seedlings, whereas SOD activity did not show a difference between experimental groups.