Alpha melanocyte stimulating hormone (αMSH) has been demonstrated to have regulatory functions in the periphery and central nervous system (CNS). αMSH plays a central role in the regulation of metabolic balance such as decreasing food intake, increasing sympathetic outflow and hypothalamic/pituitary function. Our laboratory has investigated the actions of αMSH on sympathetic and cardiovascular dynamics using anesthetized animals. In this study we determined both the acute and chronic effects of αMSH on cardiovascular and metabolic dynamics in conscious unrestrained rats. Animals were each implanted with a radio-telemetry transmitter for recording of cardiovascular parameters and subsequently instrumented with intracerebroventricular (ICV) cannulas. The acute ICV administration of αMSH significantly increased the mean arterial pressure (MAP) and heart rate (HR) when compared to artificial cerebrospinal fluid (ACSF) controls. On the other hand chronic αMSH infusion resulted in an initial increase in MAP and HR lasting for 2 days followed by a decrease in MAP. Chronic αMSH administration decreased physical activity and food intake but not weight gain. We conclude that in the conscious unrestrained animal the acute administration of αMSH increased MAP and HR, however, chronic infusion is associated with decreased MAP, physical activity and food intake.