The susceptibility of budgerigars (Melopsittacus undulatus) to graded doses of Toxoplasma gondii oocysts was studied. Sixteen budgerigars were divided into 4 groups (A–D) of 4 each. Birds in groups A–C were fed 100,000, 1,000, or 100 infective oocysts of the VEG strain of T. gondii, respectively. Budgerigars in group D were not fed oocysts and served as controls. All 4 birds in group A died (or were killed) because of acute severe enteritis 5 or 6 days after feeding oocysts (DAFO). Three of the 4 birds in group B were killed (or died) because of toxoplasmosis 9 or 14 DAFO. One budgerigar in group C and the 4 budgerigars in group D remained healthy and were killed 35 or 39 DAFO. Toxoplasma gondii was demonstrated in tissues of all budgerigars fed oocysts. The control budgerigars remained clinically normal and showed no evidence of T. gondii exposure. These results indicate that, compared to other passerines, budgerigars are relatively resistant to clinical toxoplasmosis.