Medieval, decorated floor-tiles from a number of churches in and around Roskilde, Denmark, have been compared with identically ornamented wasters of floor-tiles found inside two kilns excavated at Bistrup near Roskilde and with clay from Bistrup and Oro. For each sample the concentrations of 14 elements were determined by means of neutron activation analysis, and the results were submitted to a stepwise discriminant analysis. All floor-tile groups showed a distinct similarity to the groups of wasters and clay from Bistrup, and the result is thus compatible with the archaeological view that during the Medieval period Bistrup functioned as a production center for tiles impregnated with these particular ornamentations. See also 20-32. -- AATA