Although an illegal commodity, Australian marijuana market is estimated to be in the size of as large as $5 billion annually. Understanding the consumer behaviour of illicit drug consumption is essential in drug policy debate. Using micro unit data from the most recent National Drug Strategy Household Surveys, ordered Probit model is estimated to study the effects of some social, economic and demographic factors on the frequency of an individual’s marijuana consumption. A sequential model is also estimated that examines separately the decisions of whether to participate in regular consumption and how often to consume the drug. Results indicate that some factors may have opposite effects on the two decisions.