Following on the success of Aripiprazole with its high clinical efficacy and minimal side effects, further antipsychotic drugs (such as Bifeprunox) have been developed based on the same dopamine D2 partial agonist pharmacological profile as Aripiprazole. However clinical trials of Bifeprunox have found differing results to that of its predecessor, without the same significant clinical efficacy. This study has therefore investigated the different effects of 10 week treatment with Aripiprazole (0.75 mg/kg, 3 times per day), Bifeprunox (0.8 mg/kg, 3 times per day) and Haloperidol (0.1 mg/kg, 3 times per day) on body weight gain, food and water intake, white fat mass, and 8 week treatment on locomotor activity. Treatment with Bifeprunox was found to significantly reduce all of the measured parameters except white fat mass compared to the control group. However, Aripiprazole and Haloperidol treatment reduced water intake compared to the control, without any significant effects on the other measured parameters. These findings further demonstrate the potential pharmacological differences between Aripiprazole and Bifeprunox, and identify potential weight loss side effects and increased anxiety behaviour with Bifeprunox treatment.