Altruism is generally regarded as a beneficial characteristic involving concern for others' well-being, yet pathological altruism refers to the maladaptive tendency to prioritize others' needs at the expense of one's own well-being. While research on its risk factors remains scarce, emerging evidence suggests that narcissistic traits may contribute to pathological altruism. The present study aimed to investigate risk factors for pathological altruism by examining the predictive roles of need for social approval, grandiose narcissism (characterized by attention-seeking and inflated self-esteem), and vulnerable narcissism (marked by low self-esteem and rejection sensitivity) among individuals training in mental health disciplines. We hypothesized that vulnerable narcissism would be a stronger predictor of pathological altruism compared to grandiose narcissism. The sample consisted of 256 undergraduate students (230 female, 25 male) aged 18 to 30 (M = 22.95, SD = 2.395), enrolled in psychology, psychological counseling and social work programs, with no psychiatric diagnosis. Data were collected using the Sociodemographic Information Form, the Need for Social Approval Scale, the Healthy Selfishness and Pathological Altruism Scale, and the Pathological Narcissism Inventory. Results indicated that vulnerable narcissism was positively associated with the need for social approval and pathological altruism, whereas grandiose narcissism showed negative correlations with these variables. Hierarchical regression analyses revealed that need for social approval initially predicted pathological altruism (β = .27, t = 4.55, p < .001, ΔR2 = .08). When vulnerable narcissism was included in Model 2, the predictive role of need for social approval disappeared, while vulnerable narcissism significantly predicted pathological altruism (β = .55, t = 8.62, p < .001, ΔR2 = .21). In contrast, grandiose narcissism, entered in the third model, was not a significant predictor of pathological altruism. These findings highlight the role of vulnerable narcissism as a significant risk factor for pathological altruism.