Previous experiments have shown that group decisions are more risky than individual decisions. ‘The best lead’, according to Marquis (1962), ‘is that the members whose initial decisions were the more risky are disproportionately influential.’ The present paper investigates the influence of Machiavellianism on decisions involving risk of both individuals and groups. It seems that subjects scoring high on the Mach IV Scale tend to take higher risk decisions as individuals, and are influential in group discussions, bringing about group decisions which signify a shift in the direction of increased risk.