This is nearly two hours longer than the average week for men in other professions, and slightly longer than the average for male managers.
However, full-time female GPs work just over 43 hours a week on average, about 1.5 hours less than women in other professional occupations, and roughly an hour less than female managers.
Part-time male GPs work around 34 hours a week, compared to 29 for part-time female GPs, according to the study.
Male GPs were on call for nearly 15 hours a week if full-time, or eight hours if part-time. Female GPs were on call for around 12.5 hours full-time and 7.5 hours if part-time.
The results are based on responses from 1,871 GPs to a survey carried out in February 2004 by the University of York.