With respect to food safety, many works have studied the effectiveness of self-monitoring plans of food companies, designed using the Hazard Analysis and Critical Control Point (HACCP) method. On the other hand, indepth research has not been made concerning the adherence of the plans to HACCP standards. During our research, we evaluated 116 self-monitoring plans adopted by food companies located in the territory of the Local Health Authority (LHA) of Foggia, Italy. The general errors (terminology, philosophy and redundancy) and the specific errors (transversal plan, critical limits, hazard specificity, and lack of procedures) were standardized. Concerning the general errors, terminological errors pertain to half the plans examined, 47% include superfluous elements and 60% have repetitive subjects. With regards to the specific errors, 77% of the plans examined contained specific errors. The evaluation has pointed out the lack of comprehension of the HACCP system by the food companies and has allowed the Servizio di Igiene degli Alimenti e della Nutrizione (Food and Nutrition Health Service), in its capacity as a control body, to intervene with the companies in order to improve designing HACCP plans.