A new acoustic pulse therapy (APT) device developed specifically for treating dairy cows produces high power, deep penetration acoustic pulses distributed over a large treatment area. We show findings from a clinical assessment of the technology for treating dairy cows with (1) subclinical and (2) clinical mastitis. In study 1, overall, 116 cows of 3 herds were identified with subclinical intramammary infection and enrolled in the study with 78 cows assigned to the treatment group and 38 cows to the control. In the treatment group 70% of the cows returned to normal milk production compared with 18.4% of the control. Daily milk yield of treated cows increased significantly (P < 0.05) and the percentage of cows with SCC <300 × 10³ cells/mL was significantly higher (P < 0.001). Milk of the infected quarters appeared normal with lactose greater than 4.8%, but with no significant difference. Of the treated cows with identified bacteria, 52.6% of quarters were cured while in the control only 25% (P < 0.001). Specifically, all cows identified with Escherichia coli in the treatment group were cured, with only 60% cure with no intervention in the control. Spontaneous cure of glands infected with coagulase-negative staphylococci (CNS) and streptococci was low, while treatment successfully increased cure of CNS from 13% to 50% and that of streptococci from 18% to 36%. Of the 4 cows identified with Staphylococcus aureus, 3 were cured. In study 2, 29 cows identified with clinical mastitis were submitted either to antibiotic (n = 16) or APT treatment (n = 13). The antibiotic treatment cured 18.7% of the cows where SCC lowered to < 300 × 10³ cell/mL and 52.6% were culled. The APT treatment cured 76.9% of cows with only a single cull (7.7%). Both studies were analyzed by SAS mixed procedure and GLM. Acoustic pulse therapy was found more effective than antibiotics or no-intervention in treating clinical and subclinical mastitis in dairy cows. In contrast to current treatment options of subclinical mastitis, which require early detection, APT is an easy to use confined treatment of cow's udders. It does not require bacterial identification or discarding of milk after treatment.