Due to restrictions on antibiotic use in US organic dairy production, some producers have adopted the use of plant-derived products, or phytoceuticals, to treat mastitis. The objective of this study was to evaluate how the administration of Phyto-Mast (PM), an intramammary (IMM) phytoceutical product, affected the number and types of leukocytes present in milk of cows with induced clinical mastitis. Milk leukocytes increase when foreign materials are introduced into the gland, and monitoring these cells can help to assess immune system stimulation and mammary irritation caused by this product. Milk cellular response to PM was previously evaluated in healthy cows: no significant differences in total leukocyte count (TLC) or distribution of cell types were observed. However, it was unknown if the same response occurred in cows with clinical mastitis. Eight Holstein, Jersey, and Holstein x Jersey cows >100 d in milk were selected based on initial somatic cell counts of <400,000 cells/mL and negative bacterial cultures from all quarters. After inoculation with Streptococcus uberis and subsequent evidence of clinical mastitis, 2 IMM doses of PM were administered 12 h apart in the infected quarter. Quarter milk samples were collected before dosing, 12 h after the first dose, and 12, 24, 48, 72, and 96 h after the second dose. QScout Milk Leukocyte Differential tests were used to measure TLC and neutrophil, macrophage, and lymphocyte levels. Least squares means and standard errors of the data were obtained using PROC MIXED in SAS 9.3 with cow as a repeated measure. The TLC in cells/mL was 10.6 ± 1.4 million at dosing, 8.8 ± 1.8 million at 12 h after the first dose, and 9.7 ± 1.7 million at 12 h after the second dose. Neutrophils represented 78 ± 2% of the TLC at dosing, 77 ± 2% at 12 h after the first dose, and 76 ± 1% at 12 h after the second dose. No significant cellular differences were observed among these values or macrophage and lymphocyte levels. In conclusion, infection status of the treated cow did not alter the milk cellular response to the IMM phytoceutical product tested in this study.