Can I sue a doctor for misdiagnosis in California?

Yes: when the diagnostic failure fell below the standard of care and caused real harm. A missed or delayed diagnosis is negligence only if a reasonably careful practitioner in the same field would have identified the condition; California recognized failure-to-diagnose liability in Landeros v. Flood (1976) 17 Cal.3d 399.

Misdiagnosis claims turn on two expert-proven elements. First, breach: diagnosis involves judgment, so a wrong conclusion is actionable only when a reasonably careful physician in the same field, given the same presentation, would have ordered the tests or reached the diagnosis that was missed, the principle applied in Landeros v. Flood (1976) 17 Cal.3d 399. Second, causation, usually the harder element: the patient must show the delay itself changed the outcome, such as a cancer found at a later stage or a stroke window missed, not merely that the disease progressed as it would have anyway. Both elements require qualified medical expert testimony. The deadlines are unforgiving: Code of Civil Procedure section 340.5 allows one year from when the patient discovered or reasonably should have suspected wrongdoing, within a three-year outer limit, and section 364 requires 90 days' pre-suit notice. Complete records under Health and Safety Code section 123110 are the practical first step, and MICRA's cap shapes recoverable non-economic damages.

Authority: Landeros v. Flood (1976) 17 Cal.3d 399