Consideration is given to a systematic evaluation of the actual penetration of both ISO 9000 certification as well as different certification agencies in Greek industries. After identifying nearly all certified enterprises in Greece by the end of the year 2002, a large cluster of 1479 enterprises (circa 59.4% of all certifications), for which published information was available, is analysed. The data used concern both individual enterprises and demographic averages for respective industrial activities (determined by industry and sector). Statistical analysis reveals ISO 9000 to be mainly accepted in manufacture, with both services and commerce seriously lagging behind. Analysis by sector, a more detailed activity indicator, shows marked ISO 9000 penetration differences between sectors, suggesting the influence of activity-related practices as one of the major certification drivers. Although not uniform across activities, evidence is also provided relating large and profitable enterprises with certifications. Finally, analysis of all main certification agencies identified in Greece demonstrates that (with one exception) the choice of agency, although dependent on industrial activity, is mostly independent of certified enterprise's size and profitability.