A subjective expected utility model is developed to explain the gambling behaviour of bettors on Major League Baseball games in the United States. Betting activity was examined over 15 seasons, for the period 1978 - 1992. The observed overbetting of favourite teams by baseball bettors can be reconciled without abandoning the traditional assumption of risk aversion. Additionally, there is some evidence to suggest that positive skewness has a discernible influence in the decision-making process for higher odds contests.