The effect of red smudge, caused by Pyrenophora tritici-repentis (Died.) Drechs, on germination and early seedling development of four durum wheat (Triticum turgidum L. var. durum Desf.) cultivars was examined using artificially and naturally infected seeds. Rate of germination was similar for red smudged and healthy seeds. Percent germination of naturally infected, but not of artificially infected seeds, was lower for the red smudge than for the control treatments. The number of seminal roots was also lower for the naturally infected than for the control seeds. Lengths of the longest seminal root and of the coleoptile at 12 d were greater in the control than in the disease treatments, regardless of whether the seeds were naturally or artificially infected. It was concluded that red smudge of durum wheat seed reduced seedling vigour. There was transmission of P. tritici-repentis to the coleoptile but not to the true leaves. Key words: Red smudge, tan spot transmission, seedling vigour, durum wheat