A cross-linked polyacrylate polymer, referred to as absorbent gelling material (AGM), has been developed for use in hygiene paper products, such as infant diapers (nappies). The fate and effects of this polymer were studied in laboratory models of landfill and aerobic composting. Radiolabelled (14C) AGM was used to facilitate determination of fate and mass balance. Tests were conducted in 1201 reactors containing a mixture of solid waste and compost or solid waste only, and panty diaper pads. Controlled temperature and leachate recycle were used to accelerate the biological processes. AGM caused no adverse effects and most of the material remained associated with the diaper pad and surrounding waste. Very little AGM (less than 1 %) biodegraded to CO2/CH 4 under landfill conditions, while 2-4% appeared in leachate. The leachate was highly biodegradable aerobically. More of the AGM (6.4%) biodegraded to CO2 under aerobic composting conditions, while less than 1% appeared in leachate.