Phytoremediation is an effective, non-intrusive, and relatively inexpensive means of remediating soils contaminated with organic chemicals. Different plant species have different remediation capabilities, and intraspecies variations are also likely to exist. If intraspecies variation exists and is heritable, plant improvement for phytoremediation of contaminated soils should be possible. A study was undertaken to determine if variability exists among alfalfa (Medicago sativa L.) genotypes for agronomic performance in and phytoremediation of crude oil-contaminated soil and to determine the effect of contaminated soil on alfalfa growth. In one greenhouse experiment, degradation rates ranged from 33 to 56% among genotypes with 46% for the unvegetated control after one year, and two genotypes had significantly greater degradation rates than that of the unvegetated control. In a second greenhouse experiment, eight genotypes from the previous experiment were compared with their clones in uncontaminated soil. Mean total forage yield in contaminated soil was 32% of the yield of the same clones in uncontaminated soil after one year. Plants in contaminated soil also matured later and were shorter. The results indicate that overall growth is reduced in contaminated soil, but variability does exist among the genotypes tested and should be a consideration when plants are selected for phytoremediation.