We have developed an atmospheric temperature and constituent retrieval code using an efficient derivative of Fast Atmospheric Signature Code 3 coupled with the optimal estimation inversion method. This code provides arbitrary spectral resolution and instrument response function and was thoroughly tested with model generated data and then applied to the stratospheric Cryogenic Infrared Radiance Instrumentation for Shuttle (CIRRIS 1A) database. The CIRRIS 1A experiment flew aboard space shuttle mission Space Transportation System 39 in April 1991. It included a 1 cm-1 resolution midinfrared interferometer that made numerous scans of the earthlimb. A small subset of these included a survey of the stratosphere during the day at 50¿--65 ¿N latitude and during the night at 35¿--50 ¿S latitude. The retrieval code provides us with the error analysis tools necessary to determine the relative contributions of the measurements and any a priori information made available to the code. Temperature and constituent profiles are reported along with comparisons to other recent atmospheric measurements. The absence of sufficient information to retrieve certain species is also discussed. ¿ 1999 American Geophysical Union