Medicxi (MEH-DEE-CHEE) is a life sciences-focused investment firm, originally created at Index Ventures, a leading international venture capital firm with offices in London, San Francisco, Geneva, and St. Helier (Jersey).

Francesco De Rubertis joined Index at the end of 1997 to launch the firm's life sciences practice and was joined in the following years by three partners: Kevin Johnson, Michèle Ollier and David Grainger. Over the years, Index Ventures raised a total of twelve funds, with separate life sciences and technology investment teams.

In 2012, Index launched sector-specific venture funds for the first time, raising Index Ventures VI (technology focus) and Index Life VI (life sciences focus).  Pharmaceutical giant GlaxoSmithKline (NYSE: GSK) and the venture capital affiliate of the Janssen pharmaceutical companies of Johnson & Johnson (Janssen; NYSE: JNJ) both partnered with Index by investing in Index Life VI. This was a key step in the path to the founding of Medicxi as an independent venture firm.

The firm is led by its four co-founders and Partners Francesco, Kevin, Michèle, and David. Over the years, the four of them have collectively been involved in starting over fifty companies in several countries.

Medicxi opened its doors in Feb 2016, with offices in London, Geneva and St Helier.