At their workplace, nurses are exposed to a number of conflict situations. On dealing with such situations, a significant role is played by assertiveness skills. Assertiveness is the necessity of efficient communication between nurses and patients. Thus, development of these skills can enhance patient confidence in the nursing profession. The aim of the study was to determine whether there are differences in assertiveness with respect to age and sex, and whether there is and what is the connection between assertiveness, potential sources of conflict at work, conflicts due to the behavior of associates, resolving conflicts and self-assessment in resolving conflicts. The survey included 87 hospital nurses. The questionnaire included assessment of assertiveness. On processing the results, we calculated the indicators of descriptive statistics, carried out the variance analysis and t-test, and calculated Pearson's correlation coefficients. It was found that the majority of subjects expressed a medium level of assertiveness, i.e. they could be considered as relatively assertive persons. There were significant differences in assertiveness according to age of the subjects and length of service, where the oldest age group was significantly less assertive. More assertive subjects frequently observed behaviors that may be a source of conflict and problems in the organization of work. At the same time, they often had conflicts because of such behavior, which indicated that more assertive subjects were bolder and more secure. More assertive subjects believed that they were more successful in resolving conflicts than non-assertive subjects.