Numerous high-yielding modern maize varieties have been developed for Malawi. However, their performance and returns when managed under real-world conditions are generally unknown. We have used new cross section data to generate insights into the performance of these maize varieties. We first determined optimal portfolios of maize using expected utility maximisation models under a variety of smallholder preference structures. The analysis revealed a trade-off between expected returns and their variability. Modern varieties are high yielding but also pose relatively more downside risk than traditional varieties, perhaps because they are more sensitive to optimal management conditions. Despite this risk, too many smallholders focus exclusively on traditional varieties, and in particular they exclude any modern variety from their portfolio. Factors inhibiting the adoption of modern varieties were examined econometrically. With respect to policy implications, the results suggest that a mix of modern and traditional varieties could be appropriate for many smallholders, and that extension efforts could target specific groups, such as femaleheaded farm households of low socioeconomic status, which face severe constraints in the adoption of modern varieties.