PURPOSE: This study was to identity the relationships between the side effects of depression and quality of sleep among gynecological cancer patients undergoing chemotherapy. METHODS: The data was collected from 113 patients at two general hospitals within B metropolitan city. The instruments used to collect the data for the study was the 'Side Effect Scale' developed by Kwon, Young-eun; 'Depression scale' developed by Oh, Se-man, and the 'Quality of Sleep Scale' developed by Oh, Song & Kim. RESULTS: Results showed that the mean of side effects was 39.75+/-9.99, mean of depression was 9.63+/-3.93 and mean of 'quality of sleep' was 36.99+/-6.66. The quality of sleep variable showed statistically significant differences for the variables: age (F=3.203, p=.026), cancer insurance (t=-2.278, p=.025), and perceived physical condition (F=3.152, p=.047) respectively. The relationship between side effects and quality of sleep showed a low negative, but significant correlation (r=-.327, p<.001). The relationship between depression and quality of sleep also showed a low negative correlation (r=-.365, p<.001). CONCLUSION: This study shows that it is necessary to develop nursing intervention programs because it can successfully improve the quality of sleep of gynecological cancer patients undergoing chemotherapy.