3-M syndrome combines pre- and postnatal growth retardation and dysmorphic facial features with autosomal recessive inheritance. Six new patients with 3-M syndrome are described and compared with 28 cases from the literature. Our six patients have a growth pattern, which parallels that of Silver-Russell syndrome (SRS). Final height is ISD less in 3-M syndrome than in SRS. Growth hormone treatment significantly increased final height in two of our patients. 3-M syndrome can be differentiated from other types of dwarfism by clinical criteria and by the demonstration of characteristically slender long bones and foreshortened vertebral bodies. We propose that calculating the metacarpal and vertebral indices can be used to measure and document this important diagnostic feature. While the gonadal status of female patients with 3-M syndrome is completely normal, male patients have a gonadal dysfunction and sub- or infertility.