Ethnic and gender diversity is purported to be critical for innovation success, yet scant empirical evidence exists to support this claim. Surveys of executive perceptions, simulations under controlled conditions and field research through proxy metrics point to a positive relationship between diversity and innovation but suffer from significant limitations. The paucity of data-driven studies on the linkage between diversity and innovation is due to the fact that innovators are almost invisible in innovation research, in sharp contrast to entrepreneurs who figure prominently in entrepreneurship studies. The objective of this paper is to examine the issue of gender in innovation through an analysis of patent application data from geographical regions with intense innovative activity. (The issue of ethnicity is difficult to approach with publicly available data.) Patent application data are a direct -although not fully complete- metric of innovation output as they (mostly) capture technological innovations. A comprehensive analysis of the 31 top innovation hotspots in the US reveals that the percentage of women innovators is weakly correlated with the total patent output of innovation hotspots. While the correlation does not appear to be statistically significant, further equivalency tests suggests that the admittedly small effect is not negligible. The results of this exploratory study thus set the stage for a more comprehensive one that will have to be designed with a richer set of data.