IN a family-based association study we investigated transmission of a multiallelic CAG repeat in a novel neuronal potassium channel gene,hSKCa3, in 59 parent/ offspring trios. In contrast to recent reports of an association of moderately large repeats with schizophrenia in case-control studies, our findings indicate that short CAG repeats (≤ 19 repeats) are transmitted at an increased frequency to schizophrenic offspring (p= 0.014), particularly among familial cases (p= 0.007). No evidence for a parent-of-origin effect was found. Multiallelic TDT procedure showed no association of individual CAG repeats to schizophrenia. Further studies using family-based designs should clarify whetherhSKCa3is a susceptibility factor to schizophrenia or co-segregates with a major disease gene in tight linkage.