Annihilation of antiprotonic hydrogen atoms into π+ π- π0 is studied by stopping antiprotons from LEAR in hydrogen gas. Two data samples were taken. In the first data sample events were collected independently of the cascade of the {Mathematical expression} atom; in the second sample only those events are selected for which a low-energy X-ray is observed in coincidence with the final state. The latter data sample contains a large fraction of events in which a radiative transition to the 2 P level of the {Mathematical expression} atom was followed by annihilation. The former data contain comparable fractions of annihilation from S and P states. By subtraction of the P wave contribution annihilation from S states can be studied. The spin-parity analysis of the π+ π- π0 Dalitz plot shows that {Mathematical expression} annihilation from S waves proceeds dominantly via production of ρ{variant} mesons from the spin-triplet isospin-singlet state of the {Mathematical expression} atom. Strong interference with a background amplitude or an amplitude for ρ{variant}(1600) production is needed to obtain a satisfactory description of the data. The production of f2 mesons is weak. © 1990 Springer-Verlag.