The fair evaluation of employees is crucial to the well being of the organisation, the manager and the employee. This article looks at four factors that have been shown to bias the appraisal process. These factors are the style of dress of the employee vis‐a‐vis the rater, the attributions made by both rater and ratee regarding performance, the prior expectations of the supervisor regarding the employee's performance, and the effect of employee grievances on his or her subsequent evaluations. These four factors are but four of many possible biases that enter into the evaluation process because of the human dynamic. They are instructive, but more importantly they should serve to alert appraisers to the many possible biases that may be operative in them but of which they are unaware.