Titanium dioxide (TiO2) is an external marker used to estimate fecal output based on forage intake of grazing ruminants; however, its use as marker for grazing sheep still needs attention. In the present study the TiO2 role to estimate fecal output of sheep grazing annual ryegrass was tested. Two essays were conducted in sequence using the same forage and animals. Six lacaune lambs were housed in metabolic cages. Lambs were administered 1 g TiO2 in a single (at 8:30 am, essay 1), or in two daily doses (at 8:30 am and 4:30 pm, essay 2). In both essays the TiO2 administration was followed by a 7-day period to stabilize the fecal excretion of the marker and then by a 5-day period for total collection of feces. Observed and TiO2-based estimated fecal outputs were compared, with or without correction for TiO2 fecal recovery rate (kTiO2). The kTiO2 was around 1.0 and the estimated fecal outputs were similar to the observed ones (p>0.05), regardless the number of daily doses. These results suggested that TiO2, administered in single or two daily doses, can be used as an external marker in grazing sheep.