This paper examines the role that the microbiologist and microbiological testing play in implementing hazard analysis and critical control point (HACCP) programs. HACCP offers a more comprehensive and science-based alternative for controlling food safety hazards compared with traditional sanitation programs based upon good manufacturing practices. Controlling hazards under an HACCP program requires a systematic assemblage of reliable data relating to the occurrence, elimination, prevention, and reduction of hazards. These data need to be developed in a transparent environment that will ensure that the best scientific methodologies have been employed in developing the needed data. The two mechanisms used in HACCP to assess the adequacy of the database are validation studies and the verification assessments. Microbiological testing is an important mechanism for collecting data used in developing and implementing an HACCP plan. Microbial sample data can help establish standard operating procedures (SOPs) for sanitation, assess the likelihood of the occurrence of hazards, establish critical limits, and assess the validity of the HACCP plan. The use of a performance standard to assess whether microbiological hazards have been reduced to an acceptable level creates an especially important use for microbial analysis. Microbial testing is also useful in implementing an HACCP plan by helping to monitor the effectiveness of sanitation SOPs, the compliance of incoming ingredients with safety criteria, the safety of product being held for corrective action, and the safety of the finished product. The verification audits demonstrate that all control measures have been applied as designed in the HACCP plan. Although auditing HACCP records is the primary means of verification, microbial sampling can play an important role as well.