A data breach with Marshfield Clinic Health System has impacted personal identifiable information and private health information, potentially putting individuals at risk of fraud and suspicious activity. Full names, insurance information, and other sensitive data may have been impacted in the breach

Did you receive a letter from Marshfield Clinic alerting you that your information was impacted by the cybersecurity incident? Fill out the form below and join the investigation

Shub Johns & Holbrook LLP is currently investigating Marshfield Clinic Health System for an apparent failure to safeguard sensitive consumer information in a data breach that was detected on or around August 27, 2025. Marshfield Clinic, a Wisconsin-based healthcare organization, discovered that an unauthorized actor gained access to client data within Marshfield Clinic’s data systems. Through further investigation, it was determined that the breach took place between August 26 and August 27, 2025.

Though the data security breach was discovered in August, the Company did not begin notifying impacted individuals until late November 2025.

Marshfield Clinic has not indicated the approximate number of individuals impacted by the breach. Consumer information exposed in the breach may vary but can include:

• Name
• Address
• phone number
• date of birth
• insurance ID number
• medical record number
• dates of service
• treatment/diagnosis information
• lab results
• and medications

The cybercriminals responsible for the breach may have already obtained and sold the compromised consumer information. In previous data breaches, victims of data theft have noticed identity theft attempts ranging from fraudulent charges on bank accounts or credit cards, medical and/or government services ordered in their name, or their information being posted on the dark web.

Affected by the Marshfield Clinic Health System Data Breach

Have you recently received a data breach notification from the Marshfield Clinic Health System? Or have you experienced fraud potentially related to the data breach? If so, we would like to hear from you.  Please complete the contact form on this page or contact us at 610-477-8380 or [email protected].