By lambing upland ewes in May, it is possible to match the ewe's nutritional needs closely with grass growth (Newton et al 1982). Requirements for high cost housing and supplementary feeding during late pregnancy can be minimised. The resulting late born lambs should be available for sale as ‘out of season’ lamb when prices are at their highest. Delayed tupping, however, has been shown to reduce lambing performance in most breeds due to a lower ovulation rate (Land et al 1969). Ewe fertility, by contrast, is not affected as oestrus is strong with most indigenous breeds until February (Wheeler et al 1977). This experiment was designed to study the long term management requirements and performance of a late lambed (1 May to 5 June) flock and the efficacy of androstenedione (Fecundin) as a means of improving ovulation rate.