Historically, risks for allergic contact nickel dermatitis have been elevated in workplaces where exposures to soluble nickel have been high. For example, nickel dermatitis was common in the past among nickel platers. However, due to improved industrial and personal hygiene practices, more recent reports of nickel sensitivity in workplaces such as the electroplating industry have been sparse (Mathur, 1984; Fischer, 1989). Schubert et al., (1987) found only two nickel sensitive platers among 176 nickel sensitive individuals studied. A number of studies have shown nickel sulfate to be a skin sensitizer in animals, particularly in guinea pigs (Lammintausta et al., 1985; Zissu et al., 1987; Rohold et al., 1991; Nielsen et al., 1992). Dermal studies in animals suggest that sensitization to soluble nickel (nickel sulfate) may result in cross sensitization to cobalt (Cavelier et al., 1989) and that oral supplementation with zinc may lessen the sensitivity reaction of NiSO4-induced allergic dermatitis (Warner et al., 1988). Five percent nickel sulfate in petrolatum is typically used in patch tests as the threshold for elicitation of a positive skin reaction, although individual thresholds may vary (Uter et al., 1995). Soluble nickel compounds should be considered skin sensitizers in humans and care should be taken to avoid prolonged contact with nickel solutions in the workplace.