This study examined the theoretical knowledge and practical skills of different medical profession personnel and medical students in Basic Cardiac Life Support (BCLS). Two hundred twenty-four candidates who attended a BCLS course were tested in their theoretical knowledge of BCLS with 15 multiple choice questions (MCQs) as a pre-test. The same questions were included in the post-test but with a different sequence. We also evaluated each candidate during performance of single-rescuer CPR on a recording manikin, using a checklist and the recording strip from the manikin for evaluation of CPR steps and manikin performance respectively. Anesthesiologists and cardiologists demonstrated the best performance in the theoretical knowledge test followed by GPs and paramedics. In contrast, physicians, surgeons, pediatricians and medical students had comparable scores. No candidate performed all CPR steps correctly in the proper sequence. In addition, the manikin performance of all groups was poor. Nevertheless, the course significantly improved the theoretical knowledge (P < 0.0001) and performance in both CPR steps (P < 0.0005) and manikin performance (P < 0.0005). The multivariate discriminant analysis identified that experience and prior CPR training influenced significantly (P < 0.001) the degree of retention of theoretical knowledge only, but not the actual performance of basic resuscitation. It is concluded that no assumption based on previous clinical knowledge should be made for the expected CPR performance of all doctors, regardless of speciality. Formal training programs in medical schools should be considered. Our data also indicate that training is the only objective way to improve performance of all the candidates including the medical students. © 1990.