This review article summarises systems for categorisation of diagnostic errors in pathology and cytology with regard to diagnostic accuracy and the published information on human factors in pathology to date. A 12 point event-based checklist for error in diagnostic accuracy in histopathology and cytopathology is proposed derived from Dupont’s ‘Dirty Dozen’ human factor checklist, as utilised in the aerospace industry for aircraft maintenance. This human factor checklist comprises 12 human factors implicated in defects in aircraft maintenance; (i) failure of communication, (ii) complacency, (iii) lack of knowledge, (iv) distractions, (v) lack of teamwork, (vi) fatigue, (vii) lack of resources, (viii) pressure, (ix) lack of assertiveness, (x) stress, (xi) norms, and (xii) lack of awareness. The accompanying article explains practical examples of how each of these 12 human factors may cause errors in diagnostic accuracy in pathology. This checklist could be used as a template for analysis of accuracy and risks of diagnostic error in pathology either retrospectively ‘after the event’ or prospectively at the time of diagnosis. There is a need for further evaluation and validation of this proposed 12 point human factor checklist and similar systems for categorisation of diagnostic errors and diagnostic accuracy in pathology based on human factor principles.