<p>Hollow heart is a physiological disorder that affects potato tuber quality in the highlands (&gt; 3000 masl) within the tropics. In the literature, this disorder has been associated with low calcium content in soils. The present work aimed to determine the effect of Ca addition to the soil on hollow heart incidence in the tropical volcanic highlands of Costa Rica. We evaluated the effect of Ca addition as fertilizer (three different fractioned applications) on hollow heart incidence (%), tuber Ca content (mg kg⁻¹) and total potato yield (ton ha⁻¹) in two different potato farms. Soil Ca content observed in both farms assessed was lower than the reference value for cropping systems reported in the literature for Costa Rica. Ca addition significantly reduced the hollow heart incidence (%) in potato tubers assessed in both farms (up to 45% when comparing with the control without Ca). Curiously, Ca tuber content did not correlate with the hollow heart incidence (%). Our findings showed that providing Ca additions before hilling ameliorates the hollow heart (%) especially in soils with low Ca content like Andisols. Special attention should be paid to soil Ca content before the establishment of potato cropping systems in the volcanic highlands where Andisols dominate the landscapes.</p>