This work demonstrates the potential of fluorescence and confocal microscopy as techniques to quantify both the extent and duration of bioadhesion of alginate solutions to porcine oesophageal tissue using an in vitro model. The retention of low (40 kDa), medium (240 kDa) and high (416 kDa) MW alginates was quantified via three methods of analysis. Fluorimetric analysis of the dose removed from the oesophageal surface suggested that the percentage of the original dose retained at 30 min was 7.9 +/- 7.0%, 21.9 +/- 9.5% and 23.7 +/- 5.8% for the alginates in order of increasing MW. Analysis of the dose adhered at 30 min using fluorescence microscopy demonstrated that 5.5 +/- 1.9%, 7.1 +/- 2.7% and 18.2 +/- 1.7% of the original dose of the alginate solutions was retained at 30 min. The results found using confocal microscopy showed that the percentage of the original dose adhered at 30 min of the low, medium and high MW alginates were 4.5 +/- 1.9%, 7.2 +/- 5.3% and 11.8 +/- 4.3%, respectively. All techniques demonstrated significantly greater retention of the high MW solution at 30 min compared to the low MW solution. Both confocal and fluorescence microscopy may be used as techniques to evaluate the bioadhesion of liquid systems.