Parents, particularly mothers, of autistic children may be especially vulnerable to the negative effects of COVID-19. The current longitudinal study examined changes in psychological distress (anxiety, depression, stress) and marital functioning of mothers and fathers of autistic children across three time points between April and October 2020, and the extent to which pre-COVID factors predicted changes in these outcomes. Participants were 94 mothers and 58 fathers of autistic children drawn from a larger longitudinal study about family relationships and autistic children's mental health that began prior to the pandemic. Results indicated that mothers reported higher levels of psychological distress compared to fathers in July and October 2020. Although, on average, levels of psychological distress and marital functioning did not significantly change for mothers and fathers, pre-pandemic child functioning and marital satisfaction predicted individual differences in change in marital satisfaction during the pandemic for mothers. Implications of the findings are discussed.