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The association between paternal age, within six maternal age categories, and malformations reported on birth certificates was studied in 776,642 white, single live births in Upstate New York (1968-73). The association between paternal age and total malformation rate was not statistically significant (chi-square test); in some maternal age groups, however, high malformation rates occurred in the older paternal age groups (55-59 or 60+ years). Specific defect categories with some evidence for dominant inher­itance were analyzed separately. The only statistically significant associa­tion with paternal age was for syndactyly (chi-square test, p<. 05), due largely to a larger-than-expected number of defects in 50-59 year-old fathers. A relatively high frequency of polydactyly was evident in the 60 + year-old fathers (i.e., 4.25 per 1,000, vs. 0.42 per 1,000 overall rate), but the overall association was not statistically significant. Some possible interpretations of the findings are discussed.