The aim of this study was to ascertain the influence of natural zeolite, consisting mainly of clinoptilolite and mordenite, as a component of the litter material in broiler houses on the performance of the broilers and on some litter characteristics. Live weight gain, feed consumption, feed efficiency, viability and leg and body abnormalities of broilers, and litter moisture content were measured during a six-week experimental period. A broiler house was divided into 12 sections using 1 m high duralite partitions that prevented air exchange between sections and stocked with 15 birds/m(2). Natural zeolite was added to wood shavings at levels of 0% (control), 25%, 50% and 75% of total litter volume. Litter thickness was 5 cm in all groups. The addition of zeolite at all levels improved broiler performance significantly above the control. At the end of the six-week trial zeolite did not affect feed consumption significantly, (g), 3547, 3381, 3472 and 3421, but resulted in higher live weights of the broilers of from 1935 g in the control to 1970, 1996 and 1978 g for the respective zeolite treatments. Consequently, feed efficiency improved significantly from 1.83 g feed/g gain in the control to 1.71, 1.74 and 1.73 g feed/g gain in the respective zeolite treatments. No differences between treatments were recorded in vitality or in leg and body abnormalities in the chickens. Litter moisture content decreased from 36.2% in the control to 25.2, 23.6 and 21.8% in the respective zeolite treated litter. It is concluded that the inclusion of zeolitic material to litter positively affected broiler performance, poultry house conditions and litter moisture content. An inclusion rate of up to 25% zeolite is recommended in litter consisting of wood shavings.