Late maturity and high grain moisture content at harvest have been major limitations to the use of tropical maize (Zea mays L.) germplasm in temperate regions. The objective of this study was to determine if selection for reduced grain moisture content at harvest in a tropical maize population indirectly influenced grain yield potential. Two hundred sixteen temperately‐adapted S4 lines were derived in 1991 at Raleigh, NC, from Cycle 9 of recurrent phenotypic selection for reduced grain moisture at harvest in the tropical maize population TROPHY, and these were testcrossed in 1992 at Raleigh, NC, to the temperate hybrid B73Ht × Mo17Ht. Selected subsets of these testcrosses were evaluated for their agronomic potential in seven environments over two years, and their performance was compared with that of Cycle 0 S0 testcrosses as well as three public and three commercial F1 hybrids. Selected Cycle 9 S4 testcrosses had higher mean grain yield (7.14 Mg ha‒1) and lower mean grain moisture at harvest (184 g kg−1) than the Cycle 0 So testcrosses (6.77 Mg ha−1, and 189 g kg−1 respectively). The highest yielding Cycle 9 S4 testcrosses were comparable to the commercial hybrid LH132 × LH51. This study supported the conclusion that ergonomically competitive inbred lines with acceptable grain moisture content at harvest can be derived from 100% tropical germplasm.