the present research attempted to determine whether or not individuals' perceptions of serious heart disease and cancer would differentially affect health locus of control beliefs, as measured by the multidimensional health locus of control (mhlc) scales. study 1, a within-subjects design, assessed the health locus of control beliefs of 33 introductory psychology 世界杯2022赛程表淘汰赛 under three separate sets of instructions - no special instructions, "imagine having suffered a heart attack" instructions, and "imagine having cancer" instructions. as predicted, serious heart disease was seen to result in greater internal health locus of control beliefs, than cancer. cancer was seen as resulting in greater chance health locus of control beliefs than serious heart disease. both of these life-threatening illnesses were perceived as resulting in greater involvement of powerful others when compared to non life-threatening illnesses. study 2, a between subjects design, was then conducted using 94 introductory psychology 世界杯2022赛程表淘汰赛 . the results from this study generally confirmed the findings of study 1, with the exception of the nonsignificant differences found between the chance health locus of control beliefs of these three groups. study 3, a between-subjects design, was conducted using a clinical population of 20 "worried well" patients, 20 "serious heart disease" patients, and 20 "cancer" patients. the results from this study were again consistent with the findings of the previous two studies. these results appear to suggest that individuals' beliefs and attitudes about different life-threatening illnesses affect their health locus of control beliefs. treatment implications are offered as well as suggestions for further research.