A family history of a haematological malignancy (HM) is known to be a risk factor for HMs. However, collections of large families with multiple cases of varied disease types are relatively rare. We describe a collection of 12 families with dense aggregations of multiple HM subtypes. Cases were ascertained from a population based study conducted between 1972 and 1980 in Tasmania, Australia. Diagnoses were confirmed through review and re-examination of stored tissue, pathology reports, Tasmanian Cancer Registry and flow cytometry records. Family trees were generated and kinship coefficients were calculated for all pairs of affected individuals. 120 cases were found in these families. Cases diagnosed with chronic lymphocytic leukaemia (CLL) demonstrated the most significantly increased aggregation (P < 0·0001). There was also significant evidence that those individuals diagnosed at an older age (>53 years), did not aggregate together in families with disease that presented at an earlier age (<20 years) (P = 0·009).