Background <p>High-speed sintering has emerged as a promising innovation for enhancing the efficiency of dental prosthesis fabrication. However, its impact on marginal adaptation remains a critical factor in ensuring the long-term clinical success of restorations. The aim of the study to evaluate the marginal fit of high-speed and regular-speed-sintered zirconia crowns.</p> Methods <p>A maxillary right second molar on a typodont was prepared for an all-ceramic crown. A PVS impression was taken and a Type V stone master cast was fabricated. This cast was scanned via a laboratory scanner to produce 20 milled zirconia crowns. The crowns were divided into two groups (<i>n</i> = 10). Group A was subjected to a fast-sintering program, whereas group B was sintered via a conventional-speed-sintering program. Marginal fit was assessed via a stereoscopic microscope at four well-defined points (mid-distal, mid-lingual, mid-mesial, and mid-buccal) on each crown. Three readings were taken at each point. The marginal gaps of both groups were compared via the Wilcoxon signed-rank test.</p> Results <p>Statistically significant difference between groups A and B (<i>p</i> &lt; 0.001) was revealed. Although the mean marginal gap in both groups was below the clinically acceptable limit (&lt; 90&#xa0;μm), the fast-sintering program produced restorations with a larger marginal gap than the restorations sintered via the conventional program.</p> Conclusion <p>Crowns produced via both sintering programs were clinically acceptable, although the regular-speed-sintering program yielded a significantly superior marginal fit.</p>