Aim: To determine the minimal conditions (temperature-time), necessary to achieve set sanitation targets for selected microbial indicators during the continuous thermal treatment of pig slurry. Methods and Results: The effectiveness of thermal treatment between 55 and 96°C was studied using E. coli, enterococci, Sulphite-Reducing-Clostridia (SRC), Mesophilic-Culturable-Bacteria (MCB), F+specific and somatic phages. Identification of SRC and MCB was performed using 16S rRNA gene analysis. Ten minutes at 70°C or one hour at 60°C was sufficient to reduce the vegetative bacteria by 4-5 log10 but it had little effect on somatic phages nor spore-formers, dominated by Clostridium sp.. At 96°C, somatic phages were still detected but there was a reduction of 3.1 log10 for SRC and of 1.4 log10 for MCB. At 96°C, C. botulinum was identified among the thermotolerant MCB. Conclusion: Only those hygienic risks relating to mesophilic vegetative bacteria can be 28 totally eliminated from pig slurry treated at 60°C (60 minutes) or 70°C (less than 10 minutes). Significance and impact of the study: hygiene standards based on the removal of the indicators E. coli and enterococci, can easily be met by treatment as low as 60°C (enabling, a low cost treatment using heat recovery). However, even at 96°C, certain pathogens may persist.