Subjective judgements by planners and managers are a major component in the process of strategic planning. If such judgements are faulty, efforts at better strategic plans are likely to be misdirected. This paper discusses those biases which appear common to both managers and planners when they make judgements about risk. Implications of biased judgement are discussed in a planning context. Although we still do not know the best ways to elicit judgements, the paper concludes with a discussion of subjective sensitivity analysis which appears to offer some hope.