At 7 years of age, all 649 7-year-old children in a school district underwent a physical examination, a vision screening and an auditory screening. 210 of the children were previously examined in an extensive health control at 4 years of age. The purpose of the present study was to describe the children's health situation and to evaluate the special health control performed at 4 years of age. In 15% of the children, functionally important health problems were found. Visual defects were most common, comprising 7.5%, then came physical health problems such as motor disturbances, obesity, bacteriuria in 6.5%, and hearing defects in 1%. About half of the important health problems were previously known. Children who had passed the special health control at 4 years of age had fewer newly detected important health problems and more previously known ones than other children, which means that many children with above all visual defects but also motor disturbances, bacteriuria and testis retention, were detected and treated earlier than would have happened without the special control at 4 years. It is concluded that the "ordinary" preschool Child Health Services did fulfill their purpose to detect handicapping disorders in an acceptable way; by the introduction of the special health control at 4 years of age, this function was further improved.