At the University of Tokyo Hospital, an average of 956 venopunctures/day was performed for outpatients in the period between 2008 and 2011. At the outpatient clinic, the collection of blood without delay, and the prevention of contact infection, are always important matters to be addressed. For the prevention of infection, changing gloves, and wiping of tables and tourniquets with antiseptic cotton, for each patient has been performed since August 2010. Because the time required for each blood collection was prolonged about 19 sec., after the introduction of these preventive measures, we analyzed the factors which affected the waiting time at the blood collection room. The waiting time required for the blood collection between period of August and October, 2010, i.e., after the introduction of the preventive measures, was analyzed and compared with that between August and October, 2009, as the control. After the implementation of the preventive measures, the percentage of patients with waiting time of blood collection shorter than 10 min decreased from 73% to 58%. Thus, to improve the efficiency of blood collection and shorten the collection time, one collection booth was added, and the blood collection procedure was standardized. Also, the number of outpatients waiting for phlebotomy and the number of available phlebotomists are automatically transferred from the computer system for blood collection to the laboratory computer system, which, based on these data, displays an alert for the need of additional phlebotomists, when required. By the implementation of these measures, the percentage of patients with waiting time shorter than 10 min increased from 73% to 83%. From the present results, we considered that the preventive measures against contact infection could be successfully implemented, without affecting on the waiting time, and consequently, efficient management at the outpatient clinic could be achieved.