<p>Information on the genetic factors underlying chili pepper (<i>Capsicum annuum</i> L.) resistance to aphid is crucial for developing breeding programs to enhance desirable traits. This study investigated the gene effects for resistance to aphid infestation in two chili pepper crosses using generation means analysis. Six populations (P₁, P₂, F₁, F₂, BCP₁, BCP₂) were derived from a common susceptible female parent (C313) and two male parents (C367 in Cross I and C20 in Cross II). The no-choice clip cage method was used for evaluation. Results showed that aphid resistance in chili pepper is controlled by recessive polygenes with no maternal effects, and resistant parents showed partial recessiveness to susceptible ones. The gene action involved additive-duplicated epistasis. Broad-sense heritability was high (70–80%), while narrow-sense heritability was moderate (29–35%). These findings suggest that selection for aphid resistance should be conducted in advanced generations to overcome the effects of duplicate epistasis and stabilize traits.</p>