Aims: Bereavement following parental death experienced in adulthood may be associated with suicide over many years, but this risk has received scant attention. We investigated whether the risk of suicide increases among adult children around the anniversary of a parent's death. Methods: We conducted a case-crossover study used Swedish register-based longitudinal data from 1990 to 2016, based on the entire national population. Participants included all adults aged 18 to 65 years who experienced parental death and subsequently died by suicide. Conditional logistic regression was used to quantify the association between the anniversary (or preanniversary and postanniversary periods) and suicide, controlling for time-invariant confounding. All analyses were stratified by sex of the offspring. The analyses were also stratified by the sex of the deceased parent, time since parental death, age, and marital status. Data analyses were performed in June 2022. Results: Of 7694 individuals who died by suicide (76% intentional self-harm), 2255 (29%) were women, and the median (IQR) age at suicide was 55 (47-62) years. There was evidence of an anniversary reaction among women, with a 67% increase in the odds of suicide when exposed to the period from the anniversary to 2 days after the anniversary, compared with when not being exposed (odds ratio [OR], 1.67; 95% CI, 1.07-2.62). The risk was particularly pronounced among maternally bereaved women (OR, 2.29; 95% CI, 1.20-4.40) and women who were never married (OR, 2.08; 95% CI, 0.99-4.37), although the latter was not statistically significant. An increased risk of suicide from the day before up to the anniversary was observed among women bereaved between the ages of 18 and 34 years (OR, 3.46; 95% CI, 1.14-10.56) and between the ages of 50 and 65 years (OR, 2.53; 95% CI, 1.04-6.15). Men had an attenuated suicide risk for the period from the day before up to the anniversary (OR, 0.57; 95% CI, 0.36-0.92). Conclusions: Our findings in Sweden suggest that the anniversary of a parent's death is associated with an increased suicide risk among women. Women bereaved at younger or older ages, those who were maternally bereaved, and those who never married appeared to be particularly vulnerable. Families and social and health care professionals need to consider anniversary reactions in suicide prevention.