Animal models of Parkinson's disease (PD) with partial damage of the dopaminergic nigrostriatal system are very suitable for the development of neuroprotective and neurotrophic treatment strategies. Although drug-induced rotational behavior has conventionally been used for the analysis of lesioned animals, a pure behavioral test that can evaluate such animals in a drug-free state may better reflect a more natural response following lesion. In this study, an early model of PD was developed by intrastriatal injection of 12.5 microg of 6-hydroxydopamine (6-OHDA) into the left striatum. Apomorphine-induced rotational and drug-free elevated body swing behaviors were evaluated. The results of the rotational test revealed a very significant contralateral turning in the rats of the lesion group (L+V) compared with the sham-operated group (SH) (P<.0001). In addition, the results of elevated body swing test (EBST) showed a significant difference between the L+V and SH groups in the second (P<.01) and fourth weeks (P<.05) after surgery. Further analysis of correlation for the net number of rotations versus the net number of swings revealed a significant and positive correlation (r=.52) in the second week in the L+V group, but no such correlation was observed in the fourth week (r=.24). Taken together, it is concluded that despite a poor correlation at fourth week postlesion, EBST itself may be appropriate and sensitive for the evaluation of motor asymmetry in the unilateral model of early PD in rats.