This single centre prospective, cross-sectional study assessed the relatives of patients with pigment dispersion syndrome (PDS) and pigmentary glaucoma (PG) to determine the heritability of these conditions over an 11 month period. One hundred and one unrelated patients with PDS were recruited and 99 first-degree relatives living within a 100 mile radius were examined for the probability of familial transmission. Criteria for PDS were two of three signs: Krukenberg spindle, mid peripheral iris trans illumination defects and / or heavy trabecular meshwork pigmentation. All patients with pigment dispersion for other causes were excluded. Ten of the 99 (10.10%) first-degree relatives were diagnosed with PDS. Only seven families with more than two affected members were identified. A single examiner examined all family members. In affected family members Krukenberg spindles were found in 14/22 eyes (70%). Mid peripheral iris trans illumination defects were detected in 13/20 eyes (65%). Moderate to heavy trabecular meshwork pigmentation was present in 16/20 eyes (80%). This study has suggested that most cases of PDS and PG are sporadic and the risk to families is potentially lower than expected. However, not all family members were examined – those under 18 for example, so the incidence may be higher and further research is required.