About Me

Dr. Rei Tosu has been in practice at Kaplan & Widelitz Pediatrics since 2004.  She is Board Certified in Pediatrics and is a fellow of American Academy of Pediatrics.

She split her childhood years living in the U.S. and Japan and grew up bilingual in English and Japanese.  She attended Brown University in Providence, R.I. for her undergraduate studies where she received a Sc.B. in Neuroscience.  After spending a year doing research, she went on to attend Tufts University in Boston, MA and received her M.D.  In search of better weather, she moved to Orange County, CA to do her pediatric residency at University of California, Irvine and Long Beach Memorial Miller Children’s Hospital. After two years of working as a chief resident and seeing patients at UCI, she joined Kaplan & Widelitz Pediatrics in 2004.

She met her husband, currently a nephrologist in the area, while in medical school and got married during residency. She lives with her husband and their three children in Fountain Valley. She enjoys being involved with the children's schools and activities and travelling with her family.  She loves getting to know the families in the practice and watching the children grow. She feels privileged to take part in their lives and strives to provide the best care possible.


English, Japanese

Provider Specialty

Pediatrics, Primary Care



American Board of Pediatrics


University of California - Irvine Medical Center

Medical School

Tufts University School of Medicine

Locations & Affiliations


Insurances Accepted

Cigna Value/Select HMO (GNP)
Aetna Commercial HMO (GNP)
BlueShield Commercial HMO (GNP)