About
Who We Are
About Simi Regional Urgent Care
Emergency-trained, community focused care you can trust.
Simi Regional Urgent Care was founded on over 60 years of combined emergency and urgent care experience. Our leadership team brings together physician-level emergency medicine expertise and advanced practice nursing excellence to serve families throughout Simi Valley and Ventura County.
We are committed to delivering high-quality, efficient, and compassionate care. Our services bridge the gap between primary care and the emergency room.
Founding Leaders
Built on emergency medicine excellence, Stanford trained.
Dr. Jeffrey S. Peterson, Medical Director and Divina Masaquel-Santiago, NP, founded Simi Regional Urgent Care with a shared vision: provide emergency-level clinical expertise without the long ER wait.
Together, they have dedicated their careers to immediate, evidence-based treatment of acute illnesses and injuries. From world-class training to local care, we're proud to bring top-tier aid close to home.
Our Commitment to The Simi Valley Community
As founding leaders, our mission is to:
- Deliver emergency-level expertise without ER delays
- Provide accessible, same-day urgent care services
- Emergency Medicine expertise, Stanford-trained
- Serve children and adults with compassion and efficiency
Meet Our Founders
Board-Certified in Emergency Medicine, Dr. Peterson brings over two decades of frontline emergency and urgent care leadership.
- 15 years Clinical Assistant Professor, Stanford University Hospital
- Former Medical Director: Concentra & Kaiser Hospital San Francisco
- Post-doctoral fellow, Stanford Sports Medicine
Dr. Peterson combines academic rigor with real-world urgent care excellence, ensuring every patient receives prompt, expert-level care.
Divina brings over 30 years of emergency nursing experience and more than a decade as a Nurse Practitioner. Her background includes:
- Emergency Clinical Staff IV, Stanford Hospital
- Adult & Pediatric Emergency Departments
- Charge Nurse Leadership
- Certified in ACLS, PALS, TNCC, ENPC, NRP, CEN, FMCSA/DOT, BLS
- Family Nurse Practitioner, Board Certified
- Emergency Nurse Practitioner, Board Certified
She specializes in respiratory conditions, minor trauma, fractures, infections, pediatric urgent care, and occupational health evaluations. Known for her calm, patient-centered approach, Divina ensures efficient, compassionate care in fast-paced urgent care settings.
Isabella Ann Santiago, BSN, RN, is a critical care registered nurse with leadership experience in patient care coordination and interdisciplinary collaboration. She is currently pursuing a Doctor of Nursing Practice (DNP) in Family Primary Care Nurse Practitioner at Johns Hopkins University School of Nursing.
- Critical Care RN, Charge Nurse
- BSN — New York University; AS Allied Health (Honors) — Diablo Valley College
- DNP Candidate 2027
- Certifications: ACLS, BLS, PALS, NRP, ENPC, NIHSS
- Member: AANP, AACN
Our Clinical Standards & Safety Commitment
At Simi Regional Urgent Care, patient safety and evidence-based medicine guide every clinical decision we make.
Physician-Led Clinical Oversight
Our urgent care operates under Board-Certified Emergency Medicine supervision to ensure high clinical standards and patient safety.
- Established clinical protocols
- Quality assurance & peer review
- Infection prevention standards
- Medication safety procedures
- Ongoing provider competency evaluations
Evidence-Based Care & Continuous Quality Improvement
Urgent care for adults and seniors with diagnosis, treatment, and preventive services.
- Patient outcome tracking
- Return visit monitoring
- Adverse event review
- Documentation compliance
- Antibiotic stewardship practices
Through ongoing QA and QI initiatives, we continuously evaluate and improve our standards of care.
Emergency Preparedness & Advanced Clinical Training
Our providers maintain advanced emergency certifications to ensure readiness in critical situations.
Our providers are trained to recognize and stabilize serious conditions and coordinate safe transfer when needed.
Experience Outstanding Care from Emergency-Trained Providers Today
When you need prompt, compassionate medical care, our team is ready to help.
Walk in or schedule your visit online.