The genetic basis of pith characteristics in chicory (Cichorium intybus L. var. foliosum Hegi) was investigated. Quantitative trait loci (QTL) were mapped in an F2 population (565 F2 plants) derived from a cross between two inbred chicory lines. A molecular marker linkage map of this cross had previously been constructed based on 129 random amplified polymorphic DNA markers. Each F2 plant was selfed and plant characteristics were measured in the F3 populations. Although variation in pith characteristics was largely environmentally influenced, QTL for the characteristics length of pith, browning of the pith, hollow pith and apple pith were detected in many linkage groups. Interactions between QTL were found for the three characteristics: pith length, browning of the pith and hollow pith. The QTL detected confirmed the early forcing suitability of the one parent inbred line and late forcing suitability of the other.