Nurses are often considered to be lacking in assertive skills. This exploratory study compares the assertive behaviour of trained nurses at work and in general life situations. Questionnaire and interview techniques are used to investigate the behaviour of a small sample of sisters, staff nurses and enrolled nurses in general hospital settings. Trained nurses are found to be less assertive at work than in general life situations. In the work situation sisters are more assertive than staff nurses. The enrolled nurses are the least assertive of the trained nurses. The complex nature of assertive behaviour becomes apparent. Factors which promote assertiveness at work include knowledge, confidence, experience and the wearing of uniform. Factors which inhibit this behaviour are tradition, training and the hierarchical structure within the hospital. The use of assertiveness tends to be situation specific. Assertiveness is viewed as a positive behaviour and is of value to nurses, but there are mixed feelings about the usefulness of assertiveness training.