The purpose of the study is to evaluate the relationship between effective drug inventory control management and Stock outs in two leading Kenya public hospitals: Kenyatta National Hospital and Defence Forces Memorial Hospital. The study objectives were: a) to determine how policies, systems, staff capacity affect drug inventory control management in Kenya’s public hospital; and b)to establish association between inventory management and stock outs in the two hospitals. Descriptive survey design involving a mix of qualitative and quantitative research methods was used. The instruments used were self - administered questionnaires, one on one in - depth interviews and observations. The main conclusion from the study was that the relationship between stock out and determinants of drug inventory management were non-significant in both hospitals. The main recommendation from this study is that more determinants other than the ones in this study need to be evaluated to establish the real causes of drug stock outs in public hospitals.