This study evaluated 30 gallium alloy (Gallium alloy GF) and 31 amalgam (Dispersalloy) restorations over a period of 8 months in both Class I and Class II cavity preparations in 28 human subjects. At baseline, all gallium alloy and amalgam restorations were considered acceptable (Alfa) in terms of caries, anatomic form, marginal adaptation, surface texture, and bulk fracture. Postoperative sensitivity was reported in 67% of the gallium alloy restorations and in 29% of the amalgam restorations. At 8 months, 61% of the gallium alloy restorations were rated Beta for marginal adaptation, and all restorations exhibited tarnish and corrosion. With a few exceptions, the amalgam restorations were rated Alfa for those criteria. Three gallium alloy restorations had to be replaced during the evaluation period because of severe postoperative sensitivity and 39% of gallium restorations still presented some sensitivity at 8 months. Additional problems exhibited by gallim restorations were tooth fractures, tooth cracks, and marginal whitening.