Concern about yield losses in Pima cotton (Gossypium barbadense) due to Alternaria leafspot, caused by Alternaria macrospora, has increased in recent years in Arizona. The activities of the systemic fungicides that may offer protection using low rates and few applications were studied. Propiconazole, bitertanol, triadimenol, and triadimefon were evaluated in vitro on 5% V-8 agar. All fungicides reduced radial growth of A. macrospora at 10 ppm, propiconazole and triadimefol reduced radial growth at 500 ppb and none was effective at 1 ppb. In greenhouse tests, propiconazole at 135 ppm a.i. and triadimenol at 75 and 150 ppm a.i. reduced the number of lesions/leaf 99% when applied 2 days prior to inoculation; bitertanol at 150 ppm a.i. and triadimefon at 150 ppm a.i. reduced the number of lesions/leaf 58% and 69% respectively. When applied 4, 8, or 16 days prior to inoculation, propiconazole at 135 ppm a.i. and triadimenol at 150 ppm a.i. reduced the number of lesions significantly.