This article develops a phenomenological contribution to biological psychiatry. Grounded in the principles of transformation, heterogeneity, proportionality and particularity, a paradigm of phenomenological orientation allocates to biology a role different from that assumed by official Cartesian psychiatry. First, no clear definition of what is biological may be established a priori—as a general application, and useful to each and every studied phenomenon. Biology may be understood only as the experience of ununderstandable elements within consciousness, and as belonging necessarily to a whole unity of conscious experience. Second, the research agenda in biological psychiatry necessarily intersects with the investigation of the particularities of each individual clinical case with its unique characteristics. Without this, the very notion of biological psychiatry becomes merely a theoretical abstraction. Finally, the continuity of the biological agenda needs to resume the construction and investigation of psychopathological categories that cohere with the reality of the mental universe.