Besides being employed as an efficient plant growth retardant for field, garden and potted plants, paclobutrazol (PBZ) is also used in laboratory experiments, mainly in aseptic cultures, both in autoclaved and non-autoclaved form. Therefore it is not known if autoclaving can partial or completely inactivates the product, thus decreasing its efficacy. Thus a simple experiment was carried out to assess to what extent the autoclaving process can affect some growth components and dry mass accumulation and partition in sunflower seedlings, by employing the techniques of plant Growth Analysis. Autoclaving did not modify either qualitative or quantitatively any of the plant responses to PBZ as well their reversions by gibberellic acid.