AbstractWe described the general clinical course of histidinemia in a previous report. Here, we report on five patients having particular problems in the developmental aspects.Case 1 was found to have histidinemia at the age of 3 years during a clinical survey of the nature of his neurological symptoms. He has been followed up for seven years. He developed poorly in verbal expression.Case II was detected by newborn mass screening. The psychomotor development was apparently normal, but in detail, the development of fine motor and cognitive function was insufficient during the follow‐up period. Consequently, a developmental lag in visual perception, visual motor perception and spatial perception were noted in this case.Cases III, IV and V were each 3 years old, and were also diagnosed as histidinemic by newborn mass screening test; scanty attachment and various kinds of autistic behavior were noted during their clinical course.These five cases were clinically different from other non‐symptomatic patients with histidinemia.It is important to study the pathogenesis of such psychomotor abnormalities from the viewpoint of psychological care for the child