Background <p>Negative interpersonal experiences in primary healthcare may undermine trust in physicians and continuity of care, yet population-level evidence linking such experiences to healthcare avoidance remains limited. This study, therefore, quantified the prevalence of such experiences in Polish primary care and examined their association with appointment cancellations.</p> Methods <p>A large-scale, cross-sectional, quota-based online survey was conducted among 1,075 adults in Poland. Negative healthcare experiences and reasons for canceling medical appointments were summarized using two composite indices: the Index of Negative Healthcare Experiences (INHE; 0–14) and the Index of Reasons for Canceling Medical Appointments (IRCMA; 0–11). Associations with sociodemographic factors, trust in physicians, and satisfaction with care were analyzed.</p> Results <p>The most frequently reported negative experiences were a lack of empathy (43.6%), long waiting times that adversely affected health (38.0%), and feeling ignored (37.6%). The mean INHE score was 4.2 ± 4.3 (median 3.0). Higher INHE scores were associated with lower trust in physicians (<i>r</i> = -.20) and lower satisfaction with current primary care physician services (<i>r</i> = -.22; both <i>p</i> &lt; 0.001). Chronic disease (β = 0.235) and lower life satisfaction (β = -0.167) were the strongest predictors of negative experiences. The most commonly reported reasons for appointment cancellation were prior negative experiences with a physician (38.1%) and physician rudeness (36.3%).</p> Conclusions <p>In this large online sample, negative interpersonal experiences in primary care were common and were associated with lower trust in physicians and self-reported appointment cancellation.</p>