Whereas in the great majority of autosomal duplications/deficiencies a clinically recognizable dysmorphic sydrome is present, distal 3p duplication is not associated with major dysmorphic signs. We present the clinical data and molecular cytogenetic findings in two non-related patients. Diagnosis was made in a female child at the age of 5 months because of psychomotor retardation and slight dysmorphism. She also presented hydronenosis and develops no speech at the age of almost 4 years. Her partial trisomy is the result of an inverted duplication 3p22 --> 3pter (dup(3)(pter --> p26::p22(p26::p26 --> qter)). An adult woman was diagnosed at the of 80 years only on the basis of mental retardation and poor speech development, but without evident dysmorphism. In this patient the partial 3p trisomy is the unbalanced product of a 3p/17p translocation: t(3:7)(p253:p133).