Handwashing is very basic and important in controlling nosocomial infection. We researched the effect of handwashing by doctors and nurses at the UOEH Hospital. One hundred and eight doctors and 114 nurses of 19 wards were examined. The number of bacteria was determined by a palm stamp check agar plate for general bacteria before and after handwashing. The difference in the condition of microorganism contamination among the wards was found by the number of bacteria before handwashing, and by comparing the number of bacteria before and after handwashing, the effect of handwashing was determined. Handwashing by water or soap is not effective in killing bacteria. Therefore, we suggest that doctors and nurses use an effective disinfectant when washing their hands before and after contact with patients. We also think that the results noted in this paper will help doctors and nurses to have a better understanding of the importance of infection control.