A descriptive-explanatory design was employed in this study. The purpose of this study was identify the level of assertiveness and clinical stress and the relationships between assertiveness and clinical stress in nursing students. A convenient sample of 143 nursing students was used for the study. The results of this study are as follows : 1) The level of assertiveness of nursing students was 3.65 in domain of contents, 3.68 in domain of voice, and 4.13 in domain of body language. Thus the level of asertiveness of nursing students was higher in body language. 2) The level of clinical stress of nursing students was 3.73 in domain of clinical education and evaluation by professors, 3.59 in domain of nurses, 3.32 in domain of human relationships, and 3.30 in domain of environment. Thus the level of clinical stress of nursing students was higher in clinical education and evaluation by professors. 3) The assertiveness of nursing students was found significantly related to human relationships. 4) The clinical stress of nursing students was found significantly related to satisfaction of nursing, satisfaction of clinical practice and priority of candidate for nursing. 5) The assertiveness of nursing students was not found significantly related to clinical stress in nursing students.