This study was designed to replicate and extend an earlier study in wh
ich a therapy programme was carried out with two agrammatic aphasic pa
tients with sentence processing impairments suggested to be at the lev
el of mapping thematic roles and grammatical relations (Byng 1988). In
the current study one of the therapy procedures implemented in the pr
evious study was repeated with three different people with long-term '
agrammatism'. The outcome of the therapy resulted in some gains in sen
tence production and verb retrieval, but these gains varied across the
three patients. Whilst some change had taken place for each person, t
he pattern of results showed that the quality and extent of the change
was different in each case. The potential source for these difference
s is explored and the implications of the study for the necessary deve
lopment of theories about therapy are discussed.